UGC NET Environment Science [EVS] Book PDF [Sample]

DIWAKAR EDUCATION HUB
FUNDAMENTALS OF
ENVIRONMENTAL SCIENCES UNIT-1
As Per Updated Syllabus
T H E L E A R N W I T H E X P E R T I E S

FUNDAMENTALS OF ENVIRONMENTAL SCIENCES UNIT-1
COPYRIGHT DIWAKAR EDUCATION HUB Page 2
FUNDAMENTALS OF ENVIRONMENTAL SCIENCES
Definition
Environmental science is the study of the interactions between the physical, chemical, and
biological components of nature. As such, it is a multidisciplinary science: it involves a number
of disciplines like geology, hydrology, soil sciences, plant physiology, and ecology.
Environmental scientists may have training in more than one discipline; for example, a
geochemist has expertise in both geology and chemistry. Most often, the multidisciplinary
nature of environmental scientists’ work comes from collaborations they foster with other
scientists from complementary research fields.
Environmental science and engineering are evolving endeavors. When public and scientific
interests began to accelerate in the second half of the twentieth century, pollutants of any
type and in any environmental compartment were addressed on a contaminant-by-
contaminant control basis. Each law and regulation addressed a single compartment. As
evidence, the U.S. Congress passed the Clean Air Act for air, the Clean Water Act for water,
and so on. During the 1980s, this command and control paradigm continued, but added at
least an acknowledgment for the need to prevent pollution and to minimize the volume and
toxicity of wastes. All of these, along with subsequent life cycle approaches, have been aimed
at reducing risks to acceptable levels.
Importance of Environmental Science
At this current time, the world around us is changing at a very rapid pace. Some changes are
beneficial, but many of the changes are causing damage to our planet. The field of
environmental science is a valuable resource for learning more about these changes and how
they affect the world we live in.
Let's examine a major change that is currently occurring and its relationship to environmental
science. The large change is the dramatic increase in the number of humans on earth. For
most of human history, the population has been less than a million people, but the current
population has skyrocketed to over seven billion people. This equals out to seven thousand
times more people!
Due to this increase in the human population, there has also been an increase in pressure on
the natural resources and ecosystem services that we rely on for survival. Natural
resources include a variety of substances and energy sources that we take from the
environment and use. Natural resources can be divided into renewable and nonrenewable
resources. Renewable natural resources are substances that can be replenished over a period
of time, such as sunlight, wind, soil, and timber. On the other hand, nonrenewable natural
resources are substances that are in finite supply and will run out. Nonrenewable resources
include minerals and crude oils.
Due to the increase in the human population, natural resources are being used up at a more
rapid rate than in the past. Although renewable natural resources can be replenished, when
they are used too rapidly, they cannot be replenished fast enough to meet human demand.
Even worse, when nonrenewable natural resources are used too rapidly, they become closer
to running out completely and being gone forever.

Natural resources have been referred to as the 'merchandise' produced by the environment,
and in this respect, ecosystem services are the 'facilities' that we rely on to help produce the
merchandise. Ecosystem services are the environment's natural processes that provide us with
the resources we need to support life. Common ecosystem services include water and air
purification, nutrient cycling, climate regulation, pollinating of plants, and the recycling of
waste. Just like some natural resources, ecosystem services are also limited and can be used
up if not regulated.
Now, let's tie it together and think about population growth and its influence on both natural
resources and ecosystem services. As the human population increases and natural resources
and ecosystem services are used rapidly and potentially degraded, the future of humans on
earth is in jeopardy. This is one major example of why environmental science is important and
valuable.
Importance of Environmental Science
At this current time, the world around us is changing at a very rapid pace. Some changes are
beneficial, but many of the changes are causing damage to our planet. The field of
environmental science is a valuable resource for learning more about these changes and how
they affect the world we live in.
Let's examine a major change that is currently occurring and its relationship to environmental
science. The large change is the dramatic increase in the number of humans on earth. For
most of human history, the population has been less than a million people, but the current
population has skyrocketed to over seven billion people. This equals out to seven thousand
times more people!
Due to this increase in the human population, there has also been an increase in pressure on
the natural resources and ecosystem services that we rely on for survival. Natural
resources include a variety of substances and energy sources that we take from the
environment and use. Natural resources can be divided into renewable and nonrenewable
resources. Renewable natural resources are substances that can be replenished over a period
of time, such as sunlight, wind, soil, and timber. On the other hand, nonrenewable natural
resources are substances that are in finite supply and will run out. Nonrenewable resources
include minerals and crude oils.
Due to the increase in the human population, natural resources are being used up at a more
rapid rate than in the past. Although renewable natural resources can be replenished, when
they are used too rapidly, they cannot be replenished fast enough to meet human demand.
Even worse, when nonrenewable natural resources are used too rapidly, they become closer
to running out completely and being gone forever.
Natural resources have been referred to as the 'merchandise' produced by the environment,
and in this respect, ecosystem services are the 'facilities' that we rely on to help produce the
merchandise. Ecosystem services are the environment's natural processes that provide us
with the resources we need to support life. Common ecosystem services include water and air
purification, nutrient cycling, climate regulation, pollinating of plants, and the recycling of
waste. Just like some natural resources, ecosystem services are also limited and can be used
up if not regulated.

Now, let's tie it together and think about population growth and its influence on both natural
resources and ecosystem services. As the human population increases and natural resources
and ecosystem services are used rapidly and potentially degraded, the future of humans on
earth is in jeopardy. This is one major example of why environmental science is important and
valuable.
Some important definitions of environment are as under:
1. According to Boring, ‘A person’s environment consists of the sum total of the stimulation
which he receives from his conception until his death.’ Indicating that environment comprises
various types of forces such as physical, intellectual, mental, economical, political, cultural,
social, moral and emotional.
2. Douglas and Holland defined that ‘The term environment is used to describe, in aggregate,
all the external forces, influences and conditions, which affect the life, nature, behavior and
the growth, development and maturity of living organisms’.
SCOPE OF ENVIRONMENT:
The environment consists of four segments of the earth namely atmosphere, hydrosphere,
lithosphere and biosphere:
1. Atmosphere: The Atmosphere forms a distinctive protective layer about 100 km thick
around the earth. A blanket of gases called the atmosphere surrounds the earth and protects
the surface of earth from the Sun’s harmful, ultraviolet rays. It sustains life on the earth. It
also regulates temperature, preventing the earth from becoming too hot or too cold. It saves it
from the hostile environment of outer space. The atmosphere is composed of nitrogen and
oxygen besides, argon, carbon dioxide and trace gases.
The atmosphere has a marked effect on the energy balance at the surface of the Earth. It
absorbs most of the cosmic rays from outer space and a major portion of the electromagnetic
radiation from the sun. It transmits only ultraviolet, visible, near infrared radiation (300 to
2500 nm) and radio waves. (0.14 to 40 m) while filtering out tissue-damaging ultra-violate
waves below about 300 nm.
2. Hydrosphere: The Hydrosphere comprises all types of water resources oceans, seas, lakes,
rivers, streams, reservoirs, polar icecaps, glaciers, and ground water. Oceans represent 97% of
the earth’s water and about 2% of the water resources is locked in the polar icecaps and
glaciers. Only about 1% is available as fresh water as surface water in rivers, lakes, streams,
and as ground water for human use.
3. Lithosphere: Lithosphere is the outer mantle of the solid earth. It consists of minerals
occurring in the earth’s crusts and the soil e.g. minerals, organic matter, air and water.
4. Biosphere: Biosphere indicates the realm of living organisms and their interactions with
environment, viz atmosphere, hydrosphere and lithosphere.
The scope of environmental studies is very wide and it deals with many areas like i)
Conservation of natural resources, ii) ecological aspects, iii) pollution of the surrounding
natural resources, iv) controlling the pollution, v) social issues connected to it, and vi) impacts
of human population on the environment.
Elements of Environment

Environment is constituted by the interacting systems of physical, biological and cultural
elements inter-related in various ways, individually as well as collectively. These elements are:
(1) Physical elements
Physical elements are space, landforms, water bodies, climate, soils, rocks and minerals. They
determine the variable character of the human habitat, its opportunities as well as limitations.
(2) Biological elements
Biological elements such as plants, animals, microorganisms and men constitute the
biosphere.
(3) Cultural elements
Cultural elements such as economical, social and political elements are essentially manmade
features, which make the cultural background.
ENVIRONMENT STUDIES: IMPORTANCE
The environment studies make us aware about the importance of protection and conservation
of our mother earth and about the destruction due to the release of pollution into the
environment. The increase in human and animal population, industries and other issues make
the survival cumbersome. A great number of environment issues have grown in size and make
the system more complex day by day, threatening the survival of mankind on earth.
Environment studies have become significant for the following reasons:
1. Environment Issues are being of Global: It has been well recognised that environment
issues like global warming and ozone depletion, acid rain, marine pollution and biodiversity are
not merely national issues but are global issues and hence require international efforts and
cooperation to solve them.
2. Development and Environment: Development leads to Urbanization, Industrial Growth,
Telecommunication and Transportation Systems, Hi-tech Agriculture and Housing etc.
However, it has become phased out in the developed world. The North intentionally moves
their dirty factories to South to cleanse their own environment. When the West developed, it
did so perhaps in ignorance of the environmental impact of its activities. Development of the
rich countries of the world has undesirable effects on the environment of the entire world.
3. Explosive Increase in Pollution: World census reflects that one in every seven persons in
this planet lives in India. Evidently with 16 per cent of the world's population and only 2.4 per
cent of its land area, there is a heavy pressure on the natural resources including land.
Agricultural experts have recognized soil health problems like deficiency of micronutrients and
organic matter, soil salinity and damage of soil structure.
4. Need for an Alternative Solution: It is essential, specially for developing countries to find
alternative paths to an alternative goal. We need a goal as under:
1. A true goal of development with an environmentally sound and sustainable
development.
2. A goal common to all citizens of our planet earth.
3. A goal distant from the developing world in the manner it is from the over-consuming
wasteful societies of the “developed” world.

4. It is utmost important for us to save the humanity from extinction because of our
activities constricting the environment and depleting the biosphere, in the name of
development.
5. Need for Wise Planning of Development Our survival and sustenance depend on
resources availability. Hence Resources withdraw, processing and use of the products
have all to be synchronised with the ecological cycle. In any plan of development our
actions should be planned ecologically for the sustenance of the environment and
development.
6. Misra (1991) recognized four basic principles of ecology, as under:
(i) Holism,
(ii) Ecosystem,
(iii) Succession and
(iv) Conversation.
Holism has been considered as the real base of ecology. In hierarchical levels at which
interacting units of ecology are discussed, are as under:
Misra (1991) has recognised four basic requirements of environmental management as under:
1. Impact of human activities on the environment,
2. Value system,
3. Plan and design for sustainable development,
4. Environment education.
Principles and Practices provides the scientific principles, concepts, applications, and
methodologies required to understand the interrelationships of the natural world,
identify and analyze environmental problems both natural and manmade, evaluate the
relative risks associated with these problems, and examine alternative solutions (such as
renewable energy sources) for resolving and even preventing them. Frank R. Spellman
and Melissa Stoudt introduce the science of the environmental mediums of air, water,
soil, and biota to undergraduate students.
Principles and Practices brings these topics together under several major themes,
including
1. How energy conversions underlie all ecological processes
2. How the earth’s environment functions as an integrated system
3. How human activities alter natural systems
4. How the role of culture, social, and economic factors is vital to the development of
solutions
5. How human survival depends on practical ideas of stewardship and sustainability
What is atmosphere?
We all know that earth is a unique planet due to the presence of life. The air is one among the
necessary conditions for the existence of life on this planet. The air is a mixture of several
gases and it encompasses the earth from all sides. The air surrounding the earth is called the
atmosphere.
 Atmosphere is the air surrounding the earth.

 The atmosphere is a mixture of different gases. It contains life-giving gases like Oxygen
for humans and animals and carbon dioxide for plants.
 It envelops the earth all round and is held in place by the gravity of the earth.
 It helps in stopping the ultraviolet rays harmful to the life and maintains the suitable
temperature necessary for life.
 Generally, atmosphere extends up to about 1600 km from the earth’s surface. However,
99 % of the total mass of the atmosphere is confined to the height of 32 km from the
earth’s surface.
Composition of the atmosphere
 The atmosphere is made up of different gases, water vapour and dust particles.
 The composition of the atmosphere is not static and it changes according to the time
and place.
Gases of the atmosphere
Parmanent Gases of the Atmosphere
 The atmosphere is a mixture of different types of gases.
 Nitrogen and oxygen are the two main gases in the atmosphere and 99 percentage of
the atmosphere is made up of these two gases.
 Other gases like argon, carbon dioxide, neon, helium, hydrogen, etc. form the remaining
part of the atmosphere.
 The portion of the gases changes in the higher layers of the atmosphere in such a way
that oxygen will be almost negligible quantity at the heights of 120 km.
 Similarly, carbon dioxide (and water vapour) is found only up to 90 km from the surface
of the earth.

CARBON DIOXIDE:
 Carbon dioxide is meteorologically a very important gas.
 It is transparent to the incoming solar radiation (insolation) but opaque to the outgoing
terrestrial radiation.
 It absorbs a part of terrestrial radiation and reflects back some part of it towards the
earth’s surface.
 Carbon dioxide is largely responsible for the greenhouse effect.
 When the volume of other gases remains constant in the atmosphere, the volume of the
carbon dioxide has been rising in the past few decades mainly because of the burning of
fossil fuels. This rising volume of carbon dioxide is the main reason for global warming.
OZONE GAS:
 Ozone is another important component of the atmosphere found mainly between 10
and 50 km above the earth’s surface.
 It acts as a filter and absorbs the ultra-violet rays radiating from the sun and prevents
them from reaching the surface of the earth.
 The amount of ozone gas in the atmosphere is very little and is limited to the ozone layer
found in the stratosphere.
Water Vapour
 Gases form of water present in the atmosphere is called water vapour.
 It is the source of all kinds of precipitation.
 The amount of water vapour decreases with altitude. It also decreases from the equator
(or from the low latitudes) towards the poles (or towards the high latitudes).
 Its maximum amount in the atmosphere could be up to 4% which is found in the warm
and wet regions.
 Water vapour reaches in the atmosphere through evaporation and transpiration.
Evaporation takes place in the oceans, seas, rivers, ponds and lakes while transpiration
takes place from the plants, trees and living beings.
 Water vapour absorbs part of the incoming solar radiation (insolation) from the sun and
preserves the earth’s radiated heat. It thus acts like a blanket allowing the earth neither
to become too cold nor too hot.
 Water vapour also contributes to the stability and instability in the air.
Dust Particles
 Dust particles are generally found in the lower layers of the atmosphere.
 These particles are found in the form of sand, smoke-soot, oceanic salt, ash, pollen, etc.
 Higher concentration of dust particles is found in subtropical and temperate regions due
to dry winds in comparison to equatorial and polar regions.
 These dust particles help in the condensation of water vapour. During the condensation,
water vapour gets condensed in the form of droplets around these dust particles and
thus clouds are formed.
Structure of the atmosphere

FUNDAMENTALS OF
ENVIRONMENTAL SCIENCES
UNIT-I MCQS
As per updated syllabus

FUNDAMENTALS OF ENVIRONMENTAL SCIENCES UNIT-I MCQS
COPYRIGHT DIWAKAR EDUCATION Page 2
1-The following is (are) abiotic components.
a) Plants
b) Animals
c) Land
d) All of the above
Answer: c
2-The following is the solid crust or the hard
top layer of the earth.
a) Lithosphere
b) Hydrosphere
c) Atmosphere
d) Biosphere
Answer: a
3-An irregular surface with various
landforms such as mountains, plateaus,
plants, valleys, etc is
a) Hydrosphere
b) Biosphere
c) Lithosphere
d) Atmosphere
Answer: c
4-The ______ force of the earth holds the
atmosphere around it
a) Magnetic
b) Gravitational
c) Centrifugal
d) All of the above
Answer: b
5-There could be an ecosystem of
a) Large rain forest
b) Desert
c) Ocean
d) All of the above
Answer: d
6-The following is not a natural ecosystem
a) Pond
b) Desert
c) Aquarium
d) Ocean
Answer: c
7-The thickness of crust on the ocean floors
is about
a) 5km
b) 15km
c) 25km
d) 35km
Answer: a
8-The continental mass is known as
a) sial
b) sima
c) nife
d) sini
Answer: a
9-The oceanic crust is called
a) sial
b) sima
c) nife
d) sini
Answer: b
10-The innermost layer of the earth is made
up of
a) Silicon and Alumina
b) Silicon and Magnesium
c) Silicon and Nickel
d) Nickel and Iron
Answer: d
11-The rock formed when molten magma
cools
a) Sedimentary rock
b) Igneous rock
c) Metamorphic rock
d) All of the above
Answer: b
12-An example of intrusive igneous rock is
a) Granite
b) Basalt
c) Marble
d) All of the above
Answer: a

13- Igneous and Sedimentary rocks can
change into metamorphic rocks under great
____ and _____ .
a) Heat, pressure
b) Heat, temperature
c) Volume, heat
d) Volume, temperature
Answer: a
14-Under great heat and pressure,
limestone changes to
a) Granite
b) Slate
c) Marble
d) Basalt
Answer: c
15-The process of transformation of the
rock from one to another is known as
a) Rock transformation
b) Rock formation
c) Rock cycle
d) Rock recycle
Answer: c
16. At what concentration (in ppm), is
nitrogen present in the atmosphere?
a) 780,840
b) 390,420
c) 78,084
d) 900,000
Answer: a
Explanation: Nitrogen constitutes 78% of
the atmosphere. So 78% of one million =
780,840 ppm – is the concentration of
nitrogen gas in the atmosphere.
17.In the lower layers of atmosphere, what
range of wavelengths of light is
predominant?
a) Less than 100 nm
b) Greater than 300 nm
c) Between 100-300 nm
d) All wavelengths are equally present
Answer: b
Explanation: In the lower layers of
atmosphere, light of wavelengths greater
than 300nm are present and it is because of
this reason, there is generally no ozone
formation at the ground level.
18. What does the ratio of the mass of
water vapour to mass of air indicate?
a) Absolute humidity
b) Specific humidity
c) Relative humidity
d) Approximate humidity
Answer: b
Explanation: Specific humidity is the mass of
water vapour per unit mass of air mixture.
19. What is the region of mild and irregular
wind in the equatorial region known as?
a) Trade winds
b) Westerlies
c) Doldrums
d) Easterlies
Answer: c
Explanation: Doldrums are the irregular
winds and their exact location is hard to
analyse. Ships in the region of doldrums
might restrict its movement due to a lack of
proper wind.
20. “Roaring forties” is the term used to
describe which of the following winds?
a) East-to-west air winds in the southern
hemisphere
b) West-to east air winds in the northern
hemisphere
c) East-to-west air winds in the northern
hemisphere
d) West-to-east air winds in the southern
hemisphere
Answer: d
Explanation: Roaring forties found in the
southern hemisphere are strong westerly
winds caused by air displaced from the
equator to the South Pole and aid
yachtsmen in on competitions and voyages.
20. Match the following.

A. Hurricane 1. Indian Ocean and
South Pacific
B. Typhoon 2. Low level air
circulation
C. Cyclone 3. Northeastern Pacific
and Atlantic
D. Tropical Cyclone 4. Northwestern
Pacific
a) A-1; B-3; C-2; D-4
b) A-3; B-4; C-1; D-2
c) A-2; B-3; C-4; D-1
d) A-3; B-2; C-1; D-4
Answer: b
Explanation: Hurricane, typhoon, cyclone
are all used to categorise the same type of
storm but differ based on their locations
across the world. Tropical cyclone is a low
level closed air circulation which is classified
as a hurricane/typhoon/cyclone if wind
speed exceeds 120km/hr.
21. Which of the following statements is
true?
a) Troposphere is equally thick across
different parts of the world
b) Troposphere contains the ozone layer
c) Troposphere is thinner at the equator
than at the poles
d) Troposphere is thicker at the equator
than at the poles
Answer: d
Explanation: Troposphere is nearly 16-17km
thick at the equator and thins down to
approximately 8km at the poles.
22. The temperature decreases with
altitude in the stratosphere layer.
a) True
b) False
Answer: b
Explanation: Temperature slightly increases
with altitude in the stratosphere due to
absorption of UV radiations from the sun,
by the ozone layer present in the
stratosphere.
23. Which of the following indicates the
correct order of the principal layers of the
earth’s atmosphere from top to bottom?
a) Troposphere – Stratosphere –
Mesosphere – Thermosphere – Exosphere
b) Thermosphere – Stratosphere –
Troposphere – Mesosphere – Exosphere
c) Exosphere – Thermosphere –
Mesosphere – Stratosphere – Troposphere
d) Exosphere – Mesosphere –
Thermosphere – Stratosphere –
Troposphere
Answer: c
Explanation: Exosphere is the outermost
layer of the atmosphere followed by
mesosphere, thermosphere, stratosphere
and troposphere.
23. Which layer of the atmosphere is
responsible for aurora formation?
a) Ozone layer
b) Stratosphere
c) Exosphere
d) Ionosphere
Answer: d
Explanation: Ionosphere is a secondary
layer of the atmosphere which extends
through mesosphere, thermosphere and
exosphere during day time and is
responsible for aurora – natural light display
in the sky in high altitude region.
24. Which of the following mentioned
layers is NOT a homosphere?
a) Exosphere
b) Troposphere
c) Ionosphere
d) Mesosphere

[Type text] Page 1
ENVIRONMENTAL CHEMISTRY
UNIT- 2
As Per Updated Syllabus

ENVIRONMENTAL CHEMISTRY UNIT- 2
ENVIRONMENTAL CHEMISTRY
Environmental chemistry is the discipline that concerns itself with how chemicals are formed,
how they are introduced into the environment, how they change after being introduced, the
extent to which they enter and where they end up in organisms and other receptors, and the
effects they have (usually the damage they do) once they get there.
Environmental chemistry is the study of chemical processes that occur in water, air, terrestrial
and living environments, and the effects of human activity on them. It includes topics such as
astrochemistry, atmospheric chemistry, environmental modelling, geochemistry, marine
chemistry and pollution remediation.
Illustration of Environmental Chemistry definiiton
 Atmospheric Chemistry
 Aquatic Chemistry
 Soil Chemistry
 Air Pollution
 Water Pollution
 Soil Pollution

The Mission of Environmental Chemist
Environmental chemistry is the study of the chemical and biochemical phenomena that occur
in nature. It involves the understanding of how the uncontaminated environment works, and
which naturally occurring chemicals are present, in what concentrations and with what effects.
Without this it would be impossible to study accurately the effects that humans exert on the
environment through the release of chemical species. It is a multidisciplinary science that, in
addition to chemistry, involves physics, life science, agriculture, material science, public health,
sanitary engineering, and so on. More or less, it is the study of the sources, reactions,
transport, effects, and fate of chemical species in the air, water, and land, and the effect of
human activities upon the various environmental segments, such as atmosphere,
hydrosphere, lithosphere, and biosphere. Importance of the environment across the
developed countries was realized in the 1960s and reached its climax in 1970, with the
celebration of " Earth Day " under the auspices of the United Nation. From 1972 onwards, with
the conclusion of the UN Conference on Human Environment at Stockholm, the important
environmental issues were percolated across India and other developing nations. The need for
environmental education, both formal and non-formal, was keenly felt at the national level.
The objective of environmental education is to enlighten the public about the importance of
protection and conservation of our environment and about the needs to restrain human
activities that lead to indiscriminate release of pollutants into the environment. At present,
many environmental issues exist that have grown in size and complexity day by day,
threatening the survival of mankind on earth. The various incidences of such environmental
issues include London smog of 1952—killing about 4000 people, the Mediterranean sea
turning into Dead Sea in the 1950s—unable to support aquatic life, death of a number of
Japanese people because of eating fish from the Minamata Bay in the 1960s, historical

monuments and statues in Greece and Italy getting damaged by the effect of rainwater, white
marble of Taj Mahal in India
Importance of Environmental Chemistry
Environmental chemistry is a branch of chemistry that deals with the study of effect of
chemicals on environment. These include the formation of compounds, how chemicals get
into the environment, the changes they undergo once introduced into the environment, the
number of chemicals in the environment and how they enter the organisms and other things
from the environment and the damage they cause.
In other words, environmental chemistry deals with the effect of pollutants on the
environment and the ways and means to reduce the contamination. This branch of chemistry
is the study of pollutants behavior from the environmental point of view. The environmental
chemistry is further classified into main areas; measurement of pollutants, and study of the
behavior of the contaminants.
Environmental chemistry is vital as chemicals introduced into the environment proves to be
harmful not only to the environment but also to human health and economy. We have
discussed below why environmental chemistry is essential and how it benefits human health,
environment and the economy.
Importance of Environmental Chemistry for Human Health
Environmental chemistry helps to develop methods and procedures to reduce the
contaminants or the chemicals in the air, which improves the quality of air. Cleaner air with
fewer chemicals leads to less damage to the lungs. Several methods and preventive
procedures have been developed with the help of environmental chemistry to reduce the
release of hazardous substances into the water bodies, which leads to clean and
recreational drinking water. The study also helped in reducing the risk for workers working in
the chemical industries by inventing procedures which minimize the use of chemicals in
manufacturing products.
Safer products with fewer chemicals are available for consumption purposes resulting in
reduced chemical waste which results in less environmental pollution. This branch of
chemistry also helps in introducing new ways of farming using fewer chemicals and more
organic compounds to make safer food available for people across the world. It also helps to
eliminate toxic chemicals from entering the food and food chain with the help of pesticides
that are degradable and are toxic only to specific pests.
Importance of Environmental Chemistry for Environmental Safety
Many chemicals are introduced into the environment from various sources which include
pesticides, harmful emissions from factories and vehicles, in the form of chemical waste from
industries and many others.
Environmental chemistry researches into the core cause and develops methods, techniques
and tools that reduce the chemical disposal into the environment. The chemistry has also
contributed to developing green chemicals that either degrade compounds to innocuous
products or to recover them for further use. Reduced chemicals in the environment help
plants and animals to suffer less from harmful chemicals. It also helps to reduce global

warming by lowering the rate of ozone depletion and pollutant deposits in thickly populated
places. It also contributes a lot to less use of hazardous landfills that are persistent.
Importance of Environmental Chemistry for Economy and Business
Environmental chemistry is not only important to humans and the environment but is also
crucial for business and economy. It helps in finding methods and techniques to speed up the
chemical reactions using small amounts of reactants to deliver the same results and the same
price of the product.
It also helps in reducing the number of synthetic steps which enables increased production,
increase in the plant capacity while saving energy and water consumption. Using fewer
chemicals for manufacturing the products results in reduced waste which results in reduced
cost for disposing of chemical waste and toxic waste treatments. Environmental chemistry
facilitates the replacement of new and purchased raw material with derivative waste material
from other processes.
The environmental chemistry helps in developing methods and procedures which facilitates
better performance by using less raw materials to achieve the desired results. It also helps in
preventing the depletion of natural resources by reducing their use in the manufacturing
industries. The greener products that are used by using environmental chemistry can generate
more sales as they carry a safer product label.
There is a unique need for greener products, reducing chemical waste and hazardous landfills
to make the earth a safe planet for humans, plants and animals.
Environmental Compartments
To begin our discussion of the “Fundamentals of Environmental Chemistry”, a useful starting
point will be to consider the environmental chemist’s perspective. To understand the
abundance and distribution as well as the transport, reactivity, and fate of pollutants and
nutrients, it is useful to view the environment as divided into “compartments”. These
compartments represent the gas, liquid, and solid phases of matter that form heterogeneous
matrices (or “spheres”) in which pollutants and nutrients are found and through which they
move. While describing the gases that envelope the Earth as “the atmosphere” is common
(from the Greek atmos for vapor and sphaira for globe), other “spheres” may be less familiar
terms: the geological features such as rocks, soils, and sediments that represent the
“lithosphere” (from the Greek lithos for stone), water in all of its forms that creates the
“hydrosphere” (from the Greek hydor for water), and the vast diversity of living organisms
that comprise the “biosphere” (from the Greek bios for life, course or way of living). These
compartments are clearly interrelated and interdependent.
Classification of Elements
Elements
Everything from the air around us to the food that we eat, a matter is composed of several
elements, which act as the basic building blocks. Pick up any object around you and you would
be surprised at the composition of that object’s matter. Going deep into the study of matter
around us reveals many unique and interesting facts about the composition of matter.
Charting their own journey through history, elements have been known to be discovered from
time to time. We have made such advancement through the course history that we now have

almost 114 elements that are known to mankind, some of which are even man-made. So let’s
learn about all these different elements.
Defined simply, elements are the basic building blocks of matter around us. From time to time,
new elements have been discovered which have brought to light, many properties of objects
around us.
As newer elements have made their way in common knowledge of mankind, it becomes
difficult to study each and every element in individual terms. Thus, it makes sense to
categorize these into several subgroups, so that their study can be carried out in an efficient
manner. This is why the concept of classification comes into shape.
Some of the Theories for Classification of Elements
Some of the early attempts to classify them include the following theories:
Prout’s Hypothesis
First of all, came the Prout’s Hypothesis. Devised in the year 1815, hydrogen was regarded as
the ‘central’ element around which all other atoms were made.
Dobereiner’s Triads
This theory came to light in the year 1829. According to the theory, the classification was
made in such a way that each group consisted of three elements such that they owned the
same properties. Also, in each case, the atomic weight of the middle element is supposed to
be the arithmetic mean of the other two elements.
However, this theory suffered a major limitation as Dobereiner could classify only 9 elements
in such manner, out of all that were known at the time. Therefore, new theories had to be
introduced.

Newland’s Octaves
Also known as the Law of Octaves, this theory was suggested in the year 1864. Newland
suggested that elements should be arranged in order of increasing atomic masses. After such
arrangement, every eighth element in the arrangement would have same properties as the
first element in the arrangement, which follows the order of musical notes.
However, this theory could only apply up to the element calcium, after which, it failed to hold
true for the others. Also, noble gases that were discovered later completely disturbed the
existing arrangement. As a result, new arrangements had to be introduced.
Lother Meyer’s Atomic Volume Curve
The law came in the year 1869 and expressed the existing elements in the form of a curve
between the atomic mass of the element and atomic volume. As per this theory, Lother
concluded that all elements which hold the same properties came to occupy the same position
on the curve.
Mendeleev’s Periodic Table
At the time of Mendeleef, only 63 elements had been discovered. He deduced that the
physical and chemical properties are a periodic function of their atomic masses. Therefore,
Mendeleev presented a systematic way to study existing elements.
He also allowed spaces for elements that were yet to be discovered, which proved to be a very
practical way. However, there were some limitations with his theory nevertheless. His position
of hydrogen in alkali metals and unjustified position of certain elements proved to be a
limitation of his theory. Consequently, modern arrangements came into existence.
Stoichiometry
Stoichiometry is a section of chemistry that involves using relationships between reactants
and/or products in a chemical reaction to determine desired quantitative data. In
Greek, stoikhein means element and metron means measure, so stoichiometry literally
translated means the measure of elements. In order to use stoichiometry to run calculations
about chemical reactions, it is important to first understand the relationships that exist
between products and reactants and why they exist, which require understanding how to
balance reactions.
Stoichiometry is the part of chemistry that studies amounts of substances that are involved
in reactions. You might be looking at the amounts of substances before the reaction. You
might be looking at the amount of material that is produced by the reaction. Stoichiometry is
all about the numbers.
All reactions are dependent on how much stuff you have. Stoichiometry helps you figure out
how much of a compound you will need, or maybe how much you started with. We want to
take the time to explain that reactions depend on the compounds involved and how much of
each compound is needed.
Stoichiometry is the field of chemistry that is concerned with the relative quantities of
reactants and products in chemical reactions. For any balanced chemical reaction, whole
numbers (coefficients) are used to show the quantities (generally in moles ) of both the
reactants and products. For example, when oxygen and hydrogen react to produce water, one
mole of oxygen reacts with two moles of hydrogen to produce two moles of water.

In addition, stoichiometry can be used to find quantities such as the amount of products that
can be produced with a given amount of reactants and percent yield. Upcoming concepts will
explain how to calculate the amount of products that can be produced given certain
information.
The relationship between the products and reactants in a balanced chemical equation is very
important in understanding the nature of the reaction. This relationship tells us what materials
and how much of them are needed for a reaction to proceed. Reaction stoichiometry
describes the quantitative relationship among substances as they participate in various
chemical reactions.
Stoichiometric Coefficients
In a balanced reaction, both sides of the equation have the same number of elements. The
stoichiometric coefficient is the number written in front of atoms, ion and molecules in a
chemical reaction to balance the number of each element on both the reactant and product
sides of the equation. Though the stoichiometric coefficients can be fractions, whole numbers
are frequently used and often preferred. This stoichiometric coefficients are useful since they
establish the mole ratio between reactants and products. In the balanced equation:
2Na(s)+2HCl(aq)→2NaCl(aq)+H2(g)2Na(s)+2HCl(aq)→2NaCl(aq)+H2(g)
we can determine that 2 moles of HClHCl will react with 2 moles of Na(s)Na(s) to form 2 moles
of NaCl(aq)NaCl(aq) and 1 mole of H2(g)H2(g). If we know how many moles of NaNa we start
out with, we can use the ratio of 2 moles of NaClNaCl to 2 moles of Na to determine how
many moles of NaClNaCl were produced or we can use the ration of 1 mole of H2H2 to 2
moles of NaNa to convert to NaClNaCl. This is known as the coefficient factor. The balanced
equation makes it possible to convert information about one reactant or product to
quantitative data about another element. Understanding this is essential to solving
stoichiometric problems.
Gibbs
“Gibbs free energy is a function of both the enthalpy, which is the energy possessed by a
mixture of chemicals in a system, and the entropy, or disorder, of the system”.
When you pull a rock using a rope and a pulley, you raise the height of the rock. In mechanics,
we would say that we increased the potential energy of the rock. This is because if we release
it, the rock will gain speed as it falls. If the rock hits a nail that is partly inserted on the floor,
the nail will penetrate the floor further. We would say that the rock did work on the nail
because the original potential energy of the rock was used to insert the nail in the floor.
Similarly, the Gibbs free energy is the energy available in a substance to do work. However,
this work does not involve mechanical work, meaning the substance does not expand or
contract to push on something. It refers to the 'chemical work' involved in chemical reactions.
One could think of chemical work as the energy involved in transforming one chemical into
another. The Gibbs free energy is a chemical potential energy in a substance. It is defined by
the equation:
G = H - TS

ENVIRONMENTAL CHEMISTRY UNIT-II MCQs
ENVIRONMENTAL
CHEMISTRY UNIT-II MCQs

1. Photochemical smog normally does not
contain
(a) Chlorofluorocarbons
(b) Peroxyacetyl nitrate
(c) Ozone
(d) Acrolein
Answer: (a)
2. Depletion of the ozone layer is caused
due to
(a) Ferrocene
(b) Fullerenes
(c) Freons
(d) Polyhalogens
Answer: (c)
3. Find the incorrect statement
(a) BOD value of clean water is less than
5 ppm
(b) Drinking water pH should be between
5.5-9.5
(c) carbon, sulphur and nitrogen oxides
are the most widespread air
pollutants
(d) dissolved oxygen concentration
below 5 ppm is ideal for the growth
of fish
Answer: (d)
4. Find the secondary pollutant among
these
(a) PAN
(b) N2O
(c) SO2
(d) CO2
Answer: (a)
5. The reaction responsible for the radiant
energy of the Sun is
(a) nuclear fission
(b) nuclear fusion
(c) chemical reaction
(d) combustion
Answer: (b)
6. Alum’s capacity to purify water is due to
(a) softens hard water
(b) pathogenic bacteria gets destroyed
(c) impurities’ coagulation
(d) it improves taste
Answer: (c)
7. The coldest region of the atmosphere
(a) Troposphere
(b) Thermosphere
(c) Stratosphere
(d) Mesosphere
Answer: (d)
8. Which of the oxide of nitrogen is not a
common pollutant?
(a) N2O5
(b) N2O
(c) NO
(d) NO2
Answer: (a)
9. The compound essential for the process
of photosynthesis has this element
(a) Ca
(b) Ba
(c) Fe
(d) Mg
Answer: (d)
10. In the air, N2 and O2 occur naturally but
they do not react to form oxides of nitrogen
because
(a) oxides of nitrogen are unstable
(b) catalyst is required for the reaction
(c) the reaction is endothermic
(d) N2 and O2 do not react with each
other
Answer: (c)
11. Find the successive elements of the
periodic table with ionisation energies,
2372, 520 and 890 kJ per mol respectively
(a) Li, Be, B
(b) H, He, Li
(c) B, C, N
(d) He, Li, Be
Answer: (d)

12. In the modern periodic table, the
number of period of the element is the
same as
(a) principal quantum number
(b) atomic number
(c) azimuthal quantum number
(d) atomic mass
Answer: (a)
13. For the same value of n, the penetration
power of orbital follows the order
(a) s = p = d = f
(b) p > s > d > f
(c) f < d < p < s
(d) s < p < d < f
Answer: (c)
14. The correct order of electronegativity is
(a) Cl > F > O > Br
(b) F > O > Cl > Br
(c) F > Cl > Br > O
(d) O > F > Cl > Br
Answer: (b)
15. Which one is the most acidic among
these?
(a) MgO
(b) CaO
(c) Al2O3
(d) Na2O
Answer: (c)
16. Which one will have the highest 2nd
ionisation energy?
(a) 1s2
2s2
2p6
3s1
(b) 1s2
2s2
2p4
(c) 1s2
2s2
2p6
(d) 1s2
2s2
2p6
3s2
Answer: (a)
17. Elements in the same column of the
periodic table have:
a) Similar valence shell electron
configuration
b) Same value of highest principal quantum
number
c) Same number of nucleons
d) All of the mentioned
Answer: a
Explanation: The elements having similar
valence shell electrons have similar
chemical properties like reactivity, nature of
bonds in their molecules etc. Hence in the
modern periodic table, they were grouped
in vertical columns called ‘groups’.
18. As we move down a group,
electronegativity of elements generally:
a) Increases
b) Decreases
c) Increases and then decreases
d) Decreases and then increases
Answer: a
Explanation: As we move down a group,
atomic size increases which means that the
valence electrons are much farther from
the nucleus and hence experience less force
of attraction. Hence the electronegativity
decreases down the group.
19. How many periods are there in a
modern periodic table?
a) 5
b) 6
c) 7
d) 8
Answer: c
Explanation: Modern periodic table places
elements having the same maximum
principal quantum number in one period.
There are seven periods, though the
seventh period consists of many unstable
artificial elements.
19. Temporary IUPAC systematic symbol for
the synthetic element 117 is:
a) Uuh
b) Uns
c) Uus
d) Une
Answer: c
Explanation: IUPAC has assigned temporary

systematic name Ununseptium [=Un(1)
+un(1) + sept(7) + ium] to the element with
atomic number 117. It belongs to group 17
of the periodic table and is predicted to be
a halogen. As of 2015, its discovery has not
been officially confirmed.
20. There are seventeen non-metals in the
periodic table. Unlike metals in the same
period, they have higher:
a) Atomic number
b) Atomic size
c) Electropositivity
d) All of the mentioned
Answer: a
Explanation: Non-metals are located at the
right end of their respective periods. As we
move from left to right in a period or from
top to bottom in a group, atomic number
increases. Due to increasing charge on the
nucleus, atomic size also decreases on
moving right in a period. This is also the
reason of increasing electronegativity or
decreasing electropositivity.
21. d-block elements generally show
multiple oxidation states. An exception to
this is:
a) Zinc
b) Mercury
c) Copper
d) None of the mentioned
Answer: d
Explanation: Due to a small increase in
successive ionization enthalpies, most d-
block elements exist in multiple oxidation
states. However, Zn(I) compounds are very
rare and the ion exists in a dimeric form.
22. Uranium and Thorium are two
important elements in the nuclear power
industry. In which block of the modern
periodic table are they placed?
a) s-block
b) p-block
c) d-block
d) f-block
Answer: d
Explanation: Ground state Uranium and
Thorium atoms have partially or totally
empty 5f-orbitals. They are members of the
actinide family and their naturally occurring
isotopes are radioactive.
23. Moving down a group, which of the
following properties generally diminishes?
a) Electronegativity
b) Metallic character
c) Atomic radius
d) Molar mass
Answer: a
Explanation: Due to the addition of one
shell on moving down a group, the
neighbourhood of the atom is better
shielded by the electrons from an attractive
pull of the nucleus.
24. Radon is the sixth member of group 18
of the modern periodic table. Unlike other
members of this group, Radon:
a) is solid near room temperature
b) is radioactive
c) possess high chemical reactivity
d) all of the mentioned
Answer: b
Explanation: Radon is a radioactive noble-
gas at room temperatures. It is one of
densest gases and the only naturally
occurring radioactive gas. However, its
daughter nuclei are solids. Not many
compounds of Radon are known.
25. Ionization energy decreases down the
group. It is the energy required by an
isolated gaseous atom to form an anion.
a) True
b) False
Answer: b
Explanation: Ionization energy is the energy
required by an isolated gaseous atom to
lose the least tightly bound electron to form

ENVIRONMENTAL BIOLOGY
UNIT-3
As per the updated syllabus

ENVIRONMENTAL BIOLOGY UNIT-3
Environmental Biology
Environmental Biology is a Physical Science at the intersection of environmental science,
ecology, evolution, and global change. Environmental biology examines the ways organisms,
species, and communities influence, and are impacted by, natural and human-altered
ecosystems.
Environmental biologists study the habitats, evolution and adaptations of living organisms.
Bachelor's degree programs serve as entry points to this field, but graduate degree programs
are commonly required for research positions and career advancement.
Ecology is the study of the interactions between living organisms and their environment.
These interactions, in turn, affect the distribution and abundance of organisms. Ecologists
study a tremendous variety of organisms and environments from microorganisms in the soil or
a puddle of water to plants and animals in a forest or ocean. Since human activity often has a
detrimental impact on the natural world, ecologists are often involved in identifying and
finding solutions to environmental problems.
Inside Environmental Biology
The interdisciplinary field of environmental biology focuses on the relationships among plants,
animals and their surroundings, including their responses to environmental stimuli.
Environmental biology is closely linked to and often coupled with evolutionary biology, since
both involve an exploration of how organisms adapt to changing conditions.
Environmental biologists may specialize in a single ecosystem, such as wetlands or forests, or
in the human-wildlife interface created through development, agriculture and other man-
made systems. Environmental biologists often work to preserve natural landscapes and
biodiversity, protect wildlife populations and reverse ecosystem degradation.
Ecology
Ecology is a branch of science, including human science, population, community, ecosystem,
and biosphere. Ecology is the study of organisms, the environment and how the organisms
interact with each other and their environment. It is studied at various levels, such as
organism, population, community, biosphere, and ecosystem.
Ecologist’s primary goal is to improve their understanding of life processes, adaptations and
habitats, interactions and biodiversity of organisms.
Let us have a detailed look at the ecology notes provided here and explore the concept of
ecology.
Biotic and Abiotic Factors
The main aim of ecology is to understand the distribution of biotic and abiotic factors of living
things in the environment. The biotic and abiotic factors include the living and non-living
factors and their interaction with the environment.

Biotic components
Biotic components are living factors of an ecosystem. A few examples of biotic components
include bacteria, animals, birds, fungi, plants, etc.
Abiotic components
Abiotic components are non-living chemical and physical factors of an ecosystem. These
components could be acquired from the atmosphere, lithosphere, and hydrosphere. A few
examples of abiotic components include sunlight, soil, air, moisture minerals, and more.
Living organisms are grouped into biotic components, whereas non-living components like
sunlight, water, topography are listed under abiotic components.
Types of Ecology

Different Types of Ecology
Ecology can be classified into different types. The different types of ecology are given below:
Global Ecology
It deals with interactions among earth’s ecosystems, land, atmosphere, and oceans. It helps to
understand the large-scale interactions and their influence on the planet.
Landscape Ecology
It deals with the exchange of energy, materials, organisms, and other products of ecosystems.
Landscape ecology throws light on the role of human impacts on the landscape structures and
functions.
Ecosystem Ecology
It deals with the entire ecosystem, including the study of living and non-living components and
their relationship with the environment. This science research how ecosystems work, their
interactions, etc.
Community Ecology
It deals with how community structure is modified by interactions among living organisms.
Ecology community is made up of two or more populations of different species living in a
particular geographic area.
Population Ecology
It deals with factors that alter and impact the genetic composition and the size of the
population of organisms. Ecologists are interested in fluctuations in the size of a population,
the growth of a population and any other interactions with the population.
In biology, a population can be defined as a set of individuals of the same species living in a
given place at a given time. Births and immigration are the main factors that increase the
population and death and emigration are the main factors that decrease the population.
Population ecology examines the population distribution and density. Population density is the
number of individuals in a given volume or area. This helps in determining whether a particular
species is in endanger or its number is to be controlled and resources to be replenished.

Organismal Ecology
Organismal ecology is the study of an individual organism’s behaviour, morphology,
physiology, etc. in response to environmental challenges. It looks at how individual organisms
interact with biotic and abiotic components. Ecologists research how organisms are adapted
to these non-living and living components of their surroundings.
Individual species are related to various adaptations like physiological
adaptation, morphological adaptation, and behavioural adaptation.
Molecular Ecology
The study of ecology focuses on the production of proteins and how these proteins affect the
organisms and their environment. This happens at the molecular level.
DNA forms the proteins that interact with each other and the environment. These interactions
give rise to some complex organisms.
Human Ecology
It focuses on the relationship between humans and the environment. It emphasizes the impact
human beings have on the environment and gives knowledge on how we can improve
ourselves for the betterment of humans and the environment.
Niche Construction
It deals with the study of how organisms alter the environment for the benefit of themselves
and other living beings. For eg, termites create a 6 feet tall mound and at the same time feed
and protect their entire population.
Importance of Ecology
The following reasons explain the importance of ecology:
Conservation of Environment
Ecology helps us to understand how our actions affect the environment. It shows the
individuals the extent of damage we cause to the environment.
Lack of understanding of ecology has led to the degradation of land and the environment. It
has also led to the extinction and endangerment of certain species. For eg., dinosaurs, white
shark, mammoths, etc. Thus, the study of the environment and organisms helps us to protect
them from any damage and danger.
Resource Allocation
With the knowledge of ecology, we are able to know which resources are necessary for the
survival of different organisms. Lack of ecological knowledge has led to scarcity and
deprivation of these resources, leading to competition.
Energy Conservation
All organisms require energy for their growth and development. Lack of ecological
understanding leads to the over-exploitation of energy resources such as light, nutrition, and
radiation, leading to its depletion.
Proper knowledge of ecological requirements prevents the unnecessary wastage of energy
resources, thereby, conserving energy for future purposes.

Eco-Friendliness
Ecology encourages harmonious living within the species and the adoption of a lifestyle that
protects the ecology of life.
Ecology as an interdisciplinary science
Ecology is an interdisciplinary science which studies the interactions between all living beings
and their environment, but also the interactions of living beings among them. These
interactions are biophysical and biochemical. When people are living beings, except those
interactions are reviewed and social interactions.
Biology studies living organisms. Regularities of processes in complex natural environment and
in living organisms, explore different aspects of physics, chemistry, biology and agricultural
sciences using applied mathematics, informatics and computer equipment. When considering
the human as a living organism in its social environment, we use the knowledge they have
accumulated from medical and socio-economic sciences.
The concepts of ecology and pollution are separated and ecology is defined as the study of the
complex relationships between living organisms and their organic and inorganic environment.
The community of living organisms in an ecosystem is called a biocoenosis, and is a balanced
system of predators and prey, producers and consumers. This balance is called homoeostasis.
Changes in the balance can lead to a new balance, which may be better or worse than the
previous one, or the complete breakdown of the system. Pollution is a factor which can
produce changes in a balanced ecosystem.
Ecology is the study of the ways organisms (biotic factors) and their environments (abiotics
factors) interact. It is a multidisciplinary science because of all the other fields you need to be
aware of to grasp its concepts. To understand these interactions, you have to first be able to
understand the different parts. For the organisms this means biochemistry and biology,
including genetics, botany, animal physiology, animal behaviour, microbiology. For the
environments this means geochemistry, weather patterns, nutrient cycles, geological
processes, human impact (in terms of physically changing our environments and also the
pollution of water, soil, and air).
When we talk about interactions between these two, we can look at adaptation and evolution
of individual populations/species, successional changes in environment types (from say plain
to forest over time), changes in biodiversity and overall ecosystem health/resilience.
The study of ecology is important for nature conservation and resource management
(agriculture, forestry, fisheries, etc.), and ultimately to the creation of a stable and egalitarian
society with a strong economy; disease, poverty, inequality, and exploitation result from
degraded environments and the following resource shortages.
Ecology, or ecological science, is the scientific study of the distribution and abundance of living
organisms and how the distribution and abundance are affected by interactions between the
organisms and their environment.
The environment of an organism includes both physical properties, which can be described as
the sum of local abiotic factors such as insolation (sunlight), climate, and geology, as well as
the other organisms that share its habitat.

Ecology is usually considered a branch of biology, the general science that studies living
organisms.
Organisms can be studied at many different levels, from proteins and nucleic acids (in
biochemistry and molecular biology), to cells (in cellular biology), to individuals (in botany,
zoology, and other similar disciplines), and finally at the level of populations, communities, and
ecosystems, to the biosphere as a whole; these latter strata are the primary subjects of
ecological inquiries.
Ecology is a multi-disciplinary science.
Because of its focus on the higher levels of the organization of life on earth and on the
interrelations between organisms and their environment, ecology draws heavily on many
other branches of science, especially geology and geography, meteorology, pedology,
chemistry, and physics.
Thus, ecology is considered by some to be a holistic science, one that over-arches older
disciplines such as biology which in this view become sub-disciplines contributing to ecological
knowledge.
The Origin Of Life
The earth was formed about five billion years ago. At that time it was extremely hot. The
existence of life in any form at that high temperature was not possible. As such, two questions
arise pertaining to life:
1. How did life originate on earth?
2. How did primitive organisms evolve into new forms resulting in the evolution of a
variety of organisms on earth.
Chemosynthetic Theory of Origin of Life
Several theories have been put forth to explain the origin of life. The widely accepted theory is
the Chemosynthetic theory of origin of life, proposed by A.I. Oparin. Other theories such as the
theory of Spontaneous Generation are of historical importance only.
Chemosynthetic Theory
Life might have originated at first on earth through a series of combinations of chemical
substances in the distant past and it all happened in water.
The earth originated about 5 billion years ago.
It was initially made up of hot gases and vapours of various chemicals. z Gradually it cooled
down and a solid crust was formed. z The early atmosphere contained ammonia (NH3), water
vapour (H2O), hydrogen (H2), methane (CH4). At that time there was no free oxygen. This sort
of atmosphere (with methane, ammonia and hydrogen) is still found on Jupiter and Saturn
(Fig. 1.1). z Heavy rains fell on the hot surface of earth, and over a very very long period the
water bodies appeared that still contained hot water.
Methane and ammonia from the atmosphere dissolved in the water of the seas. z In this
water, chemical reactions occurred and gave rise to amino acids, nitrogenous bases, sugars
and fatty acids which further reacted and combined to give rise to biomolecules of life such as
proteins and nucleic acids.
Probable stages in the origin of life

First stage
The sources of energy were the ultraviolet rays or electric discharge (lightening) or heat. Either
alone or a combination of these energy sources caused reactions that produced complex
organic compounds (including amino acids) from a mixture of ammonia (NH3), methane (CH4),
water (H2O) and hydrogen (H2). The amino acids are the building blocks of proteins which are
the main components of protoplasm.
Second Stage
Simple organic molecules combined to form large molecules which included peptides (leading
to the formation of proteins), sugars, starch and fat molecules.
Third stage
The large molecules of different kinds combined together to form multi-molecular heaps or
complexes. Some simple fat molecules arranged themselves around this molecular complex in
a sort of membrane. It was observed in the laboratory experiments that when such complexes
reached a certain size they separated from the surrounding solution in the form of what were
termed “coacervate drops” of microscopic size, moving in the liquid with a definite boundary
(coacervate means “heap” referring to the combining together of the molecules).
Now, some sort of “metabolism” could occur within these coacervates with synthesis of
certain substances and breakdown of others. The latter (i.e. breakdown reactions) could
provide energy.
Some of the earliest formed proteins might have acted like enzymes and would have affected
the rates of reactions. It is also believed that RNA molecules might have shown enzymatic
activity in the “primordial soup” of chemical compounds. Such molecules have been termed
ribozymes.
Fourth stage Some sort of nucleoproteins or nucleic acids may have evolved by random
combinations which have provided two more properties to coacervate–like bodies.
These include:
chemical reactions from the nucleic acids, and
(ii) the capacity to reproduce through duplication of the nucleic acids.
Thus, cells were produced that could be called the simplest primordial life. depicts the
probable stages of origin and evolution of living beings.
The primitive “drop”–like forms of life were all heterotrophs, unable to manufacture their own
food but derived it from environment.
One of the innumerable changes in genetic makeup of the primitive heterotrophs led to the
formation of chlorophyll (green colouring matter of the leaves) molecules.
The chlorophyll–bearing units of life for the first time started using solar energy for production
of food as well as for the first time started liberating free oxygen into the atmosphere.
Early atmosphere of earth had no free oxygen, the forms until then could at best
be only “anaerobic”. Chlorophyll–bearing organisms later released free oxygen
which gave greater possibilities for life to evolve.

ENVIRONMENTAL
BIOLOGY UNIT-III MCQS
T H E L E A R N W I T H E XP E R T I E S

ENVIRONMENTAL BIOLOGY UNIT-III MCQS
1. Biodiversity can be broadly classified into
how many types?
a) 2
b) 5
c) 3
d) 4
Answer: c
Explanation: The three types are species
diversity (number of the different species
found in location), Genetic diversity
(genetic variations within a species) and
Ecological diversity (variations in the
ecosystems of regions).
2. Biodiversity is of importance as it offers:
a) Stability of ecosystems
b) Stability of atmosphere
c) Stability of species
d) Stability of research
Answer: a
Explanation: Biodiversity helps in
maintaining ecological stability. The
ecosystems have an ability to maintain its
original nature even after disturbances
occur within it, with the help of biodiversity.
3. The loss in biodiversity is not attributed
to:
a) Explosion in the human population
b) Transforming earth’s surface
c) Destruction of natural habitats
d) Use of sustainable products
Answer: d
Explanation: The ever-exploding increase in
human population leads to the
consumption of resources and exploitation
of the earth’s surface. This results in the
destruction of natural habitats and
ecosystems. The use of sustainable
alternatives is a step towards conservation.
4. Biodiversity has an aesthetic value to it.
a) True
b) False
Answer: a
Explanation: The natural beauty of the
earth has refreshing sights, taste and
odours. These add an aesthetic value; wide
varieties of colours and fragrance of
flowers, taste and colours of fruits, etc.
5. In how many ways does the conservation
of biodiversity work?
a) 5
b) 2
c) 3
d) 4
Answer: b
Explanation: The conservation methods are
broadly classified as in-situ conservation
(the species are conserved in their natural
ecosystems, which are protected) and ex-
situ conservation (breeding of new and
endangered plants/animals in controlled
conditions).
6. Which one of the following is not an in-
situ conservation method?
a) Zoo
b) National Parks
c) Biosphere Reserves
d) Sanctuaries
Answer: a
Explanation: Zoo is a controlled
environment where animals are kept. The
other 3 options are the natural habitat or
areas where the species reside.
7. Which is an advantage of ex-situ
conservation?
a) Cheap method
b) Conserve large number of species
together
c) Genetic process for breeding/long life
d) Existence in natural habitat
Answer: c
Explanation: Endangered plants/animals
can be provided the conditions required for
larger life with captive breeding and genetic
techniques for development of the species
which are healthy and more productive.

8. The area of National Parks range
between:
a) 0.61 to 7818 kms
b) 0.04 to 3162 kms
c) 0.14 to 3612 kms
d) 0.16 to 8718 kms
Answer: b
Explanation: National Parks are small
reserves maintained by the Government for
the protection of wildlife and their habitat.
0.61 to 7818 kms is the range for
sanctuaries.
9. The activities of cultivation of land,
timber harvesting is permitted in:
a) Sanctuaries
b) National Parks
c) Biosphere Reserves
d) Protected Areas
Answer: a
Explanation: Sanctuaries are the areas
where only wildlife is present. So,
cultivation, harvesting of timber, etc is
permitted only if does not interfere with
the project. In all the other 3 options, it is
prohibited.
10. Hot spot areas have:
a) Low density of biodiversity
b) Only endangered plants
c) High density of hot springs
d) High density of biodiversity
Answer: d
Explanation: There are areas with a high
density of biodiversity, which are presently
the most endangered. There are 16 hot
spots in the world and 2 in India: North East
Himalayas with 3500 endemic species and
the Western Ghats with 1600.
11. Genetically different population with
the same physical features is known as
____________
a) Ecosystem
b) Ecads
c) Community
d) Ecotype
Answer: d
Explanation: Ecotype is a population which
has different genetic features, but adapted
to specific environmental condition and
have similar physical features.
12. Niche is a place where particular
organisms live.
a) True
b) False
Answer: b
Explanation: Niche is not a place, but an
idea. It is a summary of an organism’s
requirement and tolerance. Habitat is a
place where a particular organism lives.
13. Name the group of species which
exploit the abiotic and biotic resources in a
similar way?
a) Guild
b) Ecads
c) Biomes
d) Community
Answer: a
Explanation: Guild species are need not be
taxonomically related, these are the species
which exploit the resources in a similar way.
14. Who proposed the term ecosystem?
a) Grinnel
b) Turesson
c) A.G. Tansley
d) Lindeman
Answer: c
Explanation: A.G. Tansley has given the
term ecosystem in 1935. Ecosystem
comprises of all the biotic and abiotic
components and their interactions.
15. Name the organisms that manufacture
organic compounds from simple inorganic
compounds without using sunlight?
a) Detrivores
b) Organotrophs

c) Phototrophs
d) Chemotrophs
Answer: d
Explanation: Chemotrophs is a kind of
autotroph which manufacture organic
compounds from simple inorganic
compounds without the use of
photosynthesis white phototrophs are
those autotrophs which make their food by
photosynthesis.
16. Which of the following organism eats
feces?
a) Fungus
b) Bacteria
c) Earthworm
d) Dung beetle
Answer: d
Explanation: Dung beetle belongs to the
category of detritivores, who eat dead and
decaying organic matter.
17. Which of the following type of
productivity counts the total fixation of
energy by photosynthesis?
a) Secondary productivity
b) Primary productivity
c) NPP
d) GPP
Answer: d
Explanation: GPP is gross primary
productivity, which is a measure of total
fixation of energy by means of
photosynthesis.
18. Hekistotherm vegetation is found in
which of the following region?
a) High temperature
b) Very low temperature
c) High temperature with an alternating low
temperature
d) Low temperature
Answer: c
Explanation: Hekistotherm is found in very
low temperature mainly alpine vegetation is
dominant in this region. Microtherm is the
low temperature where coniferous
vegetation is found in dominance.
19. How many number of the Biogeographic
zones are present in India?
[A] 4
[B] 8
[C] 10
[D] 15
Answer: C [10]
Explanation:
10 Biogeographic zones are Trans
Himalayan zone, Himalayan zone, Desert
zone, Semiarid zone, Western ghat zone,
Deccan plateau zone, Gangetic plain zone,
North east zone, Coastal zone and Islands
present near the shore line
20.which of the following reserves holds the
unfortunate distinction of becoming the
first tiger reserve in India to lose all its wild
tigers to poaching and forest degradation?
[A] Jim Corbett
[B] Sariska
[C] Manas
[D] Gir national park
Answer: B [Sariska]
Explanation:
Sariska Tiger Reserve is located in the state
of Rajasthan (Alwar district). In the year
1955, it was declared a wildlife reserve and
declared a National Park in 1990. It became
a part of Project Tiger in 1978
21. The collection of the same species
within an area is called a population.
a) True
b) False
Answer: a
Explanation: Population is the collection of
individuals which belongs to the same
species in a given region. The group of
populations is called communities.
22. Vegetation of tropical deciduous forest
falls under which of the following

ENVIRONMENTAL GEOSCIENCES UNIT-IV
ENVIRONMENTAL GEOSCIENCES
UNIT-IV
As per Updated Syllabus
DIWAKAR EDUCATIONHUB
T H E L E A R N W I T H E C P E R T I E S

Origin of Earth
Earth, along with the other planets, is believed to have been born 4.6 billion years ago as a
solidified cloud of dust and gases left over from the creation of the Sun. For perhaps 500
million years, the interior of Earth stayed solid and relatively cool, perhaps 2,000°F. The main
ingredients, according to the best available evidence, were iron and silicates, with small
amounts of other elements, some of them radioactive. As millions of years passed, energy
released by radioactive decay—mostly of uranium, thorium, and potassium—gradually heated
Earth, melting some of its constituents. The iron melted before the silicates, and, being
heavier, sank toward the center. This forced up the silicates that it found there. After many
years, the iron reached the center, almost 4,000 mi deep, and began to accumulate. No eyes
were around at that time to view the turmoil that must have taken place on the face of
Earth—gigantic heaves and bubblings on the surface, exploding volcanoes, and flowing lava
covering everything in sight. Finally, the iron in the center accumulated as the core. Around it,
a thin but fairly stable crust of solid rock formed as Earth cooled. Depressions in the crust were
natural basins in which water, rising from the interior of the planet through volcanoes and
fissures, collected to form the oceans. Slowly, Earth acquired its present appearance.
About 4.6 billion years ago our solar system formed from a cloud of gas and dust which slowly
contracted under the mutual gravity of all of its particles. The cloud was made largely of
hydrogen (H) with some helium (He) and small amounts of the remaining naturally occurring
chemical elements. The elements larger than He had to have been produced in a supernova.
The initial rotation or tumbling motion was accelerated as the nebula contracted, like a
spinning skater who pulls in his arms to spin faster. The contracting, rotating cloud flattened
into a disc. Within the disc, the largest concentration of matter was in the center. This became
the sun. Matter collected in smaller clumps out in the disc. These became the planets. The
proto-sun and proto-planets grew by accretion of the matter that was falling in toward the
center of mass. The solar nebula warmed as the contraction increased the pressure. As the
proto-sun grew and the pressures increased, it got hot from gravitational compression. It
started to glow red. The heat from the proto-sun heated the solar nebula, especially the inner
nebula. Eventually the pressures and temperatures in the core of the proto-sun became great
enough that hydrogen nuclei fused together to form helium. This nuclear reaction released
huge amounts of energy, as it continues to do today. The sun was born. During the T-Tauri
phase, the very strong solar wind swept most of the remaining gas and particles smaller than
about 10 m from the inner solar system leaving only the planets and asteroids. The planets
had attained almost all of their mass by this time but heavy meteor bombardment continued
for another half-billion years or so.
At the high temperatures of the inner solar nebula the small proto-planets (Mercury, Venus,
Earth, Mars) were too hot to hold the volatile gases that dominated the solar nebula. Only
refractory (high melting point) materials like iron and rocky silicates were
stable. Consequently, the terrestrial planets are made primarily of metallic cores and silicate
mantles with atmospheres thin or absent. In the outer solar nebula temperatures were cool
enough for the abundant gases to accumulate and be held by proto-planets. As a result
the Jovian planets (Jupiter, Saturn, Uranus, and Neptune) are gas giants, made mostly from
hydrogen, helium, and hydrogen compounds like methane (CH4) and ammonia (NH3).

One of the most widely accepted theories for the origin of life is the one proposed by Haldane
and Oparin. In their theory, the first life formed from a “primordial soup” of organic molecules
with the help of sunlight. During that time frame, the conditions on earth were quite different
from today. The temperature was hellish and the atmosphere lacked any oxygen.
These conditions may have sparked the first precursors to life. However, the evidence is
inconclusive and the origin of life still remains a mystery.
Mantle
The mantle comprises that part of the Earth between the Mohorovičić and the Wiechert–
Gutenberg discontinuities. It makes up 83 percent of the volume of the Earth and 67 percent
of its mass and is thus of decisive importance in determining the bulk composition of
the planet. In estimating elemental abundances in the mantle, however, the same difficulty as
with the core arises: direct sampling is not feasible. Much more geophysical data are available
for the mantle, however, and some volcanic eruptions have brought rock fragments to the
surface that have certainly been derived from this zone. The most remarkable of these
materials are the diamond-bearing inclusions found in the famous pipes, or volcanic necks,
that are mined in South Africa and Siberia. The presence of diamond, the high-pressure form
of carbon, implies a depth of origin of at least 100 kilometres (62 miles), but these inclusions
are rare. The common type of mantle-derived inclusion is peridotite, a silicate rock consisting
largely of olivine, (Mg,Fe)2SiO4, with minor amounts of orthopyroxene, (Mg,Fe)SiO3, and
diopside, CaMg(Si2O6).
Geophysical information indicates that below a depth of about 1,000 kilometres (620 miles),
the mantle behaves as an essentially homogeneous material, but above this level its physical
properties are more varied, and there is evidence for second-order discontinuities. This region
above 1,000 kilometres is frequently referred to as the upper mantle, and in recent years has
been the object of a concentrated research effort by geologists and geophysicists all over the
world. The significance of the upper mantle is that processes originating there have dramatic
effects on the surface—in the form of volcanic eruptions and some earthquakes—and less
dramatic but equally important effects within the crust, such as the introduction and
concentration of some elements, possibly leading to the formation of ore deposits. Increased
knowledge of the upper mantle thus has both scientific and economic appeal.
Geophysical data on the properties of the upper mantle suggest that it must consist essentially
of magnesium-iron silicates, probably largely olivine in the region immediately below the
crust. Olivine is not stable under very high pressures, however; it is converted to a
different phase of about 10 percent higher density and with a structure like
the mineral oxide spinel (MgA12O4). This conversion would occur in the mantle at depths of
around 400 kilometres, and a second-order discontinuity at that depth can plausibly be
ascribed to this conversion. Pyroxenes also undergo transformations to phases of greater
density at the high pressures within the mantle. Thus the mantle, although composed of
material of familiar chemical composition, consists, in its lower part at least, of different
minerals than those in the upper part.
Many estimates of the composition of the upper mantle have been made in recent years. On
the whole, the similarities are more important than the differences. All agree that the principal
components are oxides of silicon, magnesium, and iron. The differences are mainly in the

minor components such as aluminum oxide, calcium oxide, and the alkalies, and are
determined largely by theoretical considerations and the weight given to specific aspects of
the geophysical and geochemical data.
Although fairly reliable estimates exist for the abundances of the major elements in the
mantle, little is known of minor and trace elements. Knowledge of the crystal structure of
possible mantle minerals indicates that many minor and trace elements will not be readily
incorporated, however. They are therefore likely to concentrate in liquid material in the
mantle and be carried upward in solution, eventually being transported into the crust. It is
thus probable that the mantle is relatively depleted, and the crust relatively enriched, in minor
and trace elements. This is certainly true for uranium and thorium, because the amount of
these elements in the crust is almost sufficient to account for the total amount of heat flowing
out of the Earth.
The Earth’s crust
The crust is a comparatively thin shell on the surface of the Earth and makes up less than 1
percent of its total mass. Its geochemical significance is only marginally related to its bulk,
however. It has been subjected to extensive investigations, and it provides the raw materials
on which civilization depends. It is the most diverse of the geospheres, being a complex mosaic
of many rock types—igneous, sedimentary, and metamorphic—each with a wide variety of
chemical and mineralogical compositions. The surface is veneered with soils, related in
composition to the rocks from which they formed, but with important modifications because
of the smaller grain size, the presence of organic matter, and an intricate complex of living
organisms. Ultimately, man’s welfare and indeed his survival depends on the wise utilization of
the materials in the crust. Modern civilization has been erected upon the exploitation of fuels
and ore deposits, which are simply geochemical concentrations of useful elements.
Minerals
To meet the definition of "mineral" used by most geologists, a substance must meet five
requirements:
 naturally occurring
 inorganic
 solid
 definite chemical composition
 ordered internal structure
"Naturally occurring" means that people did not make it. Steel is not a mineral because it is an
alloy produced by people.
"Inorganic" means that the substance is not made by an organism. Wood and pearls are made
by organisms and thus are not minerals.
"Solid" means that it is not a liquid or a gas at standard temperature and pressure. Water is
not a mineral because it is a liquid.
"Definite chemical composition" means that all occurrences of that mineral have a chemical
composition that varies within a specific limited range. For example: the mineral halite (known
as "rock salt" when it is mined) has a chemical composition of NaCl. It is made up of an equal
number of atoms of sodium and chlorine.

"Ordered internal structure" means that the atoms in a mineral are arranged in a systematic
and repeating pattern. The structure of the mineral halite is shown in the illustration on this
page. Halite is composed of an equal ratio of sodium and chlorine atoms arranged in a cubic
pattern.
The Word "Mineral"
The word "mineral" is used in many different ways. Here are some examples:
Geologist's Definition
A formal definition of a mineral, as used by geologists would be: A naturally occurring
inorganic solid that has a definite chemical composition, and an ordered internal structure.
Geologists are able to identify minerals because they have characteristic physical properties.
Nutritionist's Definition
The word "mineral" also has a nutritional meaning, which is different from the meaning used
by geologists. A nutritionist uses the word mineral when referring to the many inorganic
substances that organisms need to grow, repair tissue, metabolize, and carry out other body
processes. Mineral nutrients for the human body include: iron, calcium, copper, sulfur,
phosphorus, magnesium and many others.
Archaic Use of "Mineral"
An archaic use of the word "mineral" comes from the Linnaean taxonomy in which all things
can be assigned to the animal, vegetable, and mineral kingdoms.
Inconsistent Use of "Mineral"
The word "mineral" is also used inconsistently. In mining, anything obtained from the ground
and used by man is considered to be a "mineral commodity" or a "mineral material." These
include: crushed stone, which is a manufactured product made from crushed rocks; lime,
which is a manufactured product made from limestone or marble (both composed of the
mineral calcite); coal which is organic; oil and gas which are organic fluids; rocks such
as granite that are mixtures of minerals; and, rocks such as obsidian which are mineraloids and
do not have a definite composition and ordered internal structure.
Mineral Commodities in Industry
2019 United States Mineral Commodity Consumption
Mineral Commodity Million Metric Tons
Crushed Stone 1,600
Sand and Gravel 980
Cement 102
Salt 57.0
Gypsum 42.0
Iron Ore 41.0
Phosphate Rock 25.0

Clays 22.0
Lime 18.0
Sulfur 9.4
Potash 5.4
Soda Ash 5.2
Barite 3.0
Copper 1.8
Lead 1.6
Values above are estimates of apparent mineral commodity consumption from the United
States Geological Survey. Many other commodities could be added to this table.
The construction industry is the largest consumer of mineral commodities. Crushed stone is
used for foundations, road base, concrete, and drainage. Sand and gravel are used in concrete
and foundations. Clays are used to make cement, bricks, and tile. Iron ore is used to make
reinforcing rods, steel beams, nails, and wire. Gypsum is used to make drywall. Dimension
stone is used for facing, curbing, flooring, stair treads, and other architectural work. These are
just a few of the many uses for these commodities in construction.
In agriculture, phosphate rock and potash are used to make fertilizer. Lime is used as an acid-
neutralizing soil treatment. Mineral nutrients are added to animal feed.
The chemical industry uses large amounts of salt, lime, and soda ash. Large amounts of metals,
clay, and mineral fillers/extenders are used in manufacturing.
Physical Properties of Minerals
There are approximately 4000 different minerals, and each of those minerals has a unique set
of physical properties. These include: color, streak, hardness, luster, diaphaneity, specific
gravity, cleavage, fracture, magnetism, solubility, and many more. These physical properties
are useful for identifying minerals. However, they are much more important in determining
the potential industrial uses of the mineral. Let's consider a few examples.
The mineral talc, when ground into a powder, is perfectly suited for use as a foot powder. It is
a soft, slippery powder so it will not cause abrasion. It has the ability to absorb moisture, oils,
and odor. It adheres to the skin and produces an astringent effect - yet it washes off easily. No
other mineral has a set of physical properties that are as suitable for this purpose.
The mineral halite, when crushed into small grains, is perfectly suited for flavoring food. It has
a salty taste that most people find pleasing. It dissolves quickly and easily, allowing its flavor to
spread through the food. It is soft, so if some does not dissolve it will not damage your teeth.
No other mineral has physical properties that are better suited for this use.
The mineral gold is perfectly suited for use in jewelry. It can be easily shaped into a custom
item of jewelry by a craftsperson. It has a pleasing yellow color that most people enjoy. It has a
bright luster that does not tarnish. Its high specific gravity gives it a nice "heft" that is

preferred by most people over lighter metals. Other metals can be used to make jewelry, but
these properties make gold an overwhelming favorite. (Some people might add that gold's
rarity and value are two additional properties that make it desirable for jewelry. However,
rarity is not a property, and its value is determined by supply and demand.)
Importance of Physical Properties
The primary characteristics of a mineral that determine its physical properties are its
composition and the strength of the bonds in its ordered internal structure. Here are some
examples:
Galena, a lead sulfide, has a much higher specific gravity than bauxite, an aluminum hydroxide.
This difference is because of their composition. Lead is much heavier than aluminum.
Diamond and graphite both consist of pure carbon. Diamond is the hardest natural mineral,
and graphite is one of the softest. This difference occurs because of the types of bonds
connecting the carbon atoms in their mineral structures. Each carbon atom in diamond is
bonded to four other carbon atoms with strong covalent bonds. Graphite has a sheet structure
in which atoms within the sheets are bonded to one another with strong covalent bonds, but
the bonds between the sheets are weak electrical bonds. When graphite is scratched the weak
bonds fail easily, making it a soft mineral.
The gemstones ruby and sapphire are color variations of the mineral corundum. These color
differences are caused by composition. When corundum contains trace amounts of chromium,
it exhibits the red color of a ruby. However, when it contains trace amounts of iron or
titanium, it exhibits the blue color of sapphire. If, at the time of crystallization, enough
titanium is present to form tiny crystals of the mineral rutile, a star sapphire may form. This
occurs when tiny crystals of rutile align systematically within the crystalline structure of the
corundum to give it a silky luster that might produce a "star" that aligns with the primary
crystallographic axis
Rock
Rock, in geology, naturally occurring and coherent aggregate of one or more minerals.
Such aggregates constitute the basic unit of which the solid Earth is composed and typically
form recognizable and mappable volumes. Rocks are commonly divided into three major
classes according to the processes that resulted in their formation. These classes are (1)
igneous rocks, which have solidified from molten material called magma; (2) sedimentary
rocks, those consisting of fragments derived from preexisting rocks or of materials precipitated
from solutions; and (3) metamorphic rocks, which have been derived from either igneous or
sedimentary rocks under conditions that caused changes in mineralogical composition,
texture, and internal structure. These three classes, in turn, are subdivided into numerous
groups and types on the basis of various factors, the most important of which are chemical,
mineralogical, and textural attributes.
General Considerations
Rock types
Igneous rocks
Igneous rocks are those that solidify from magma, a molten mixture of rock-forming minerals
and usually volatiles such as gases and steam. Since their constituent minerals are crystallized

from molten material, igneous rocks are formed at high temperatures. They originate from
processes deep within the Earth—typically at depths of about 50 to 200 kilometres (30 to 120
miles)—in the mid- to lower-crust or in the upper mantle. Igneous rocks are subdivided into
two categories: intrusive (emplaced in the crust), and extrusive (extruded onto the surface of
the land or ocean bottom), in which case the cooling molten material is called lava.
Clarke estimated that 95 percent of crustal rocks are of igneous origin (formed from molten
silicate masses, or magmas). Sedimentary rocks occur as a thin veneer on an igneous or
metamorphic basement, except where locally thickened in mountain belts.
The primordial rocks of the crust must have been essentially igneous, and the first
sedimentary rocks were derived from them by processes of weathering and erosion.
Metamorphic rocks are formed from both sedimentary and igneous rocks by transformations
due to heat and pressure at depth in the crust; unless very intense, these transformations do
not totally obliterate the primary igneous or sedimentary features.
Major components
Igneous rocks show a wide range of composition; the principal component, silica (SiO2), ranges
from about 35 percent to 80 percent among the commoner igneous rocks, and other
components also show a wide variation. They thus illustrate some quite extensive geochemical
fractionations of the elements, the fractionations that may have economic significance if they
bring about the findings of workable ore deposits.
In 1924 a comprehensive review of igneous rock composition based on compilation of over
5,000 superior analyses was published. This was in many respects the ultimate refinement of
Clarke’s initial review of 1889. It confirmed that the averages of analyses from different
continental areas are essentially identical. It also revealed significant geochemical differences
between the continental and oceanic crusts. The average of igneous rock analyses from the
oceanic islands is notably lower in silica and alkalies, and higher
in magnesium and calcium oxides, than the continental averages. This is simply a reflection of
the fact that most oceanic islands, such as Hawaii, consist almost entirely of basalts (averaging
about 50 percent silica), whereas continental areas include large granitic masses, with silica
contents around 70 percent. In terms of volumes, igneous rocks consist predominantly of two
great types, granitic and basaltic. The former essentially are confined to the continents and the
latter occur in both continents and ocean basins. The other types of igneous rocks, while many
and varied, are quantitatively insignificant and hardly affect the averages. Thus, for the major
elements, the average of over 5,000 analyses of igneous rocks is not significantly different
from the simple average of two individual rocks, a granite (G-1) and a basalt (W-1). This can be
seen from the Table, by comparing G-1 and W-1 values with those in the column headed
“Earth’s crust.”
The figures for the specific granitic (G-1) and basaltic (W-1) rocks are included in the Table
because they have been analyzed for practically all the elements in different geochemical
laboratories throughout the world. The rock G-1 was a granite from Westerly, Rhode Island,
and W-1 was a basaltic rock (specifically a diabase) from Centerville, Virginia. Several hundred
kilograms of each of these rocks were crushed to a fine powder in the laboratories of the U.S.
Geological Survey and samples distributed to analytical laboratories throughout the world, in

ENVIRONMENTAL GEOSCIENCES
UNIT-IV MCQS

ENVIRONMENTAL GEOSCIENCES UNIT-IV MCQS
1. The depth up to which the mantle is said
to exist is ________
a) 2000 km
b) 1500 km
c) 2900 km
d) 1800 km
Answer: c
Explanation: The second layer, Mantle, lies
beneath the crust and this zone starting
from the lower boundary of the crust
continues up to a depth of 2,900 km.
2. The thickness of the 2 layers of the upper
mantle is approximately said to be
________
a) 400 and 600 km
b) 300 and 500 km
c) 450 and 800 km
d) 300 and 400 km
Answer: a
Explanation: The upper mantle is further
divided into two layers of 400 and 600 km
thickness respectively.
3. The exact nature of the mantle is
completely understood.
a) True
b) False
Answer: b
Explanation: It is said that the exact nature
of the mantle is as yet incompletely
understood.
4. Which of the following is not true about
Asthenosphere?
a) It is present in the upper mantle
b) It is in solid state
c) It is the source of volcanic activity
d) It is in plastic rather than solid state
Answer: b
Explanation: It is in solid state is not true
and the remaining options are true and
they are characteristics of the
asthenosphere. In Greek, “asthenes” means
without strength and hence the name.
5. Who was the first person to tell about
the Core?
a) Graham Bell
b) Albert Einstein
c) Isaac Newton
d) R.D. Oldham
Answer: d
Explanation: The existence of the core was
suggested by R.D. Oldham in 1906 and
subsequently confirmed by other
seismologists.
6. The depth at which the core layer starts
and ends respectively is ____________
a) 2900 and 6371 km
b) 2000 and 5371 km
c) 2500 and 4771 km
d) 2000 and 5000 km
Answer: a
Explanation: The mantle extends up to the
depth of 2900 km and from that depth it is
the core that is said to be present and the
radius of the Earth is 6371 km and hence
the core is said to extend till 6371 km.
7. Which of the following is true about the
inner core?
a) It is believed to be a semi solid body
b) It is believed to be a solid body
c) It is believed to be a liquid body
d) It is believed to be a gaseous body.
Answer: b
Explanation: The inner core with a thickness
of around 1790 km is believed to be a solid
body.
8. The density of the Earth in the core
immediately after the mantle is _______
a) 8 g/cc
b) 7.6 g/cc
c) 9.9 g/cc
d) 8.7 g/cc
Answer: c
Explanation: At the base of the mantle,
density is inferred as 5.7 g/cc that jumps to
9.9 g/cc at the top of the core.

9. The layer which does not transmit the S-
waves is _______
a) Outer core
b) Crust
c) Mantle
d) Inner core
Answer: a
Explanation: The outer core behaves more
like a liquid because the S-waves from the
earthquake shocks reaching this zone are
not transmitted through this zone at all.
10. There is a hypothesis that the inner core
is made up chiefly of iron and nickel.
a) True
b) False
Answer: a
Explanation: As regards the chemical
composition of the inner core, the
hypothesis that it is made up chiefly of iron
and nickel elements has found support from
many accounts.
11. The density of the Earth at its centre is
said to be ________
a) 9.9 g/cc
b) 8.8 g/cc
c) 13 g/cc
d) 12.7 g/cc
Answer: c
Explanation: The value of density reaches
12.7 g/cc at the boundary of the inner core
and becomes 13 g/cc at the centre of the
Earth.
12. The layer which is said to support the
slow moving tectonic plates is ________
a) Asthenosphere
b) Lithosphere
c) Mohorovic sphere
d) Core layer
Answer: a
Explanation: The Asthenosphere is believed
to be located entirely in the upper mantle
and supports the slowly moving tectonic
plates.
13. What is the thickness of the inner core?
a) 790 km
b) 1790 km
c) 2790 km
d) 3790 km
Answer: b
Explanation: The inner core, is believed to
be in solid metallic state and is said have
thickness of about 1790 km.
14. The layer which is believed to be the
source of volcanic activity is ________
a) Inner core
b) Outer core
c) Asthenosphere
d) Mohorovicic layer
Answer: c
Explanation: The asthenosphere is believed
to be the source of much volcanic activity
and many other processes. It is said be to
located completely in the upper mantle.
15. What is the thickness of the crust under
the mountainous areas and in particular the
Himalayas?
a) 50-55 km
b) 60-65 km
c) 70-75 km
d) 30-35 km
Answer: c
Explanation: It is believed that the thickness
of the crust under the Himalayas is 70 to 75
km and under the Hindukush it is said to be
60 km thick.
16. The discontinuity which marks the lower
boundary of the crust is ______________
a) Crust-Mantle discontinuity
b) Oceanic discontinuity
c) SIAL layer
d) Mohorovicic discontinuity
Answer: d
Explanation: Mohorovicic discontinuity
marks the lower boundary of the crust
which is the first layer of the Earth.

17. The granite layer in the crust is also
referred to as ____________
a) SIAL
b) SIMA
c) SLAM
d) SILA
Answer: a
Explanation: SIAL stands for Silicon and
Aluminium and as per the name it is made
up of the two elements and hence the
name.
18. The density of the oceanic layer in the
crust is said to be ____________
a) 3.00 g/cc
b) 2.50 g/cc
c) 1.90 g/cc
d) 2.00 g/cc
Answer: a
Explanation: The oceanic crust is estimated
to have a volume of 2.54*109 cc with an
average density of 3.00 g/cc.
19. The depth at which the Mohorovicic
discontinuity occurs is ____________
a) 90-100 km
b) 50-60 km
c) 70-80 km
d) 30-40 km
Answer: d
Explanation: Mohorovicic discontinuity
from seismic evidence is determined that it
is approximately at a depth of 30-40 km.
20. What is the speed attained by the P-
waves in the C-layer under the Continental
crust?
a) 6 to 7.6 km/sec
b) 3 to 4 km/sec
c) 5 to 6.3 km/sec
d) 1.8 to 2.5 km/sec
Answer: a
Explanation: The C-layer is the lowermost
layer of the continental crust and here the
P-waves attain velocity as high as 6 to 7.6
km/sec.
21. The layer under the continental crust
with the density of 2.4 to 2.6 g/cc is?
a) A-layer
b) B-layer
c) C-layer
d) D-layer
Answer: b
Explanation: The Middle layer or B-layer of
the continental crust is relatively dense
compared to A-layer and the density is said
to be 2.4 to 2.6 g/cc.
22. The expansion of SIMA is ____________
a) Silicon and Manganese
b) Silicon and Magnesium
c) Strontium and Manganese
d) Strontium and Magnesium
Answer: b
Explanation: Silicon and Magnesium. The C-
layer under the continental crust is rich in
Silicon and Magnesium and hence the layer
is also sometimes called SIMA.
23. The oceanic layer is the extension of C-
layer of the continental crust and A and B-
layer are mostly absent.
a) True
b) False
Answer: a
Explanation: The oceanic crust is the
extension of C-layer of the continental crust
that makes the top layer of the oceans in
most cases, A and B layers being practically
absent from there.
24. The least dense layer among the layers
under the continental crust is
____________
a) A-layer
b) B-layer
c) C-layer
d) D-layer
Answer: a
Explanation: The A or the upper layer is
between 2 to 10 km thick and is of low
density, 2.00 g/cc.

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