Sciencequiz08ppt
- 1. 1. When and why are days longer in the northern hemisphere as compared to those in the southern hemisphere on earth? During 21st March till 23rd September. The reason for this difference in the lengths of a day is that the earth’s axis of Rotation is tilted with respect to its plane of revolution around the Sun which is also the reason why different seasons occur on earth. As you can guess the opposite Happens during the remaing six months of the year for the same reason
- 2. 2. What is the difference between a sea breeze and a land breeze and when do they occur? Few hours after the sun rise as the land gets hot ,the air just above starts moving upwards and lets the cool air over the sea move towards the land and the breeze so set in is called the sea breeze. Similarly towards the evening as the land gets cooler faster than the sea, the air over the sea move upwards due to convection and the cool air over the land move downwards towards the sea producing the land breeze
- 3. 3. What is the structure of earth’s atmosphere, and what is the purpose of ozone layer? The earth’s atmosphere consists of the Troposphere, the Stratosphere, the Ozone Layer, the Mesosphere and the Ionosphere The Ozone layer prevents the UV radiation from reaching the earth’s lower regions and thus protect the life on earth
- 4. 4. What is greenhouse effect and what is the main cause for it? The heating of the earth’s lower atmosphere due to the absorption of the earth emitted IR radiation by certain gases is called the greenhouse effect. Most common gases responsible for the effect are carbon di oxide and methane
- 5. 5. What is smog and in which part of the year is it maximum? Smog is a combined word for SMOKY-FOG. It appears mostly in wintry days due to burning of large amounts of coal. It is hazardous as it is a combination of smoke and sulfur di oxide. In colder weather the water vapour in the atmosphere condenses and thus becomes a blanket preventing the air moving upwards.
- 6. 6. How can you show that light needs no medium to travel but sound requires a medium? If you keep an electric bell with a small lighted bulb in a Jar and slowly create vacuum inside the jar, nothing happens to the light from the bulb but the sound of the bell slowly diminishes and finally dies down. Also we know that the sunlight reaches us on earth without any problem even though the in between space is empty. Sound needs a medium as it is directly related to the compression and rarefaction of the medium that travels as sound waves
- 7. 7. Why does the image formed in a pinhole camera appear inverted? Because the light travels along straight line
- 8. 8.If you keep two plane mirrors inclined at an angle of 600 and place an object in the middle how many images do form? FIVE The formula for finding the number of Images is N = (360 / ang btwn the mirors)-1
- 9. 9.What is the difference between a real and a virtual image? What is the image formed when you stand in front of a plane mirror? If the reflected rays meet at a point on the same side of the object only then a Real image is formed. If the reflected rays appear to meet at a point behind the mirror then the image is said to be virtual The image formed in a plane mirror is Virtual Mirror Image object
- 10. 10.What is the nature of the image formed by a concave mirror when the object is placed beyond the centre of curvature and where is the image formed? The image is Real, Inverted and Smaller than the object. It is formed between the Focus and center of curvature
- 11. 11.How are the states of matter related to the arrangement of molecules in a given substance? And why are they so arranged? Molecules are very closely packed in solids, loosely packed in liquids and are somewhat free to move around, while in gases they are completely free to occupy all the available space, with the inter molecular forces being least. This arrangement depends entirely on their kinetic energy, which changes with the addition or subtraction of the heat energy ,which is the most important agency for change of state of substances
- 12. 12. If you keep equal amount of hot water at the same temperature in three different vessels one made of steel, one of copper and the other of plastic all exposed for an hour in the open shade, which will cool faster and why? The one in the copper vessel cools fastest as the heat is lost both by conduction and convection. Next is steel because it takes little more time to cool as compared to copper. The one in the plastic vessel cannot lose heat by conduction and thus remains hot for longest time
- 13. 13.In winter why does one wear a woolen sweater to keep oneself warm? Instead if you wear two cotton shirts will it have the same effect? Woolen wear shields heat from escaping from the body and thus the body keeps warm. Cotton being made of cellulose fibre lets air pass through more easily and thus loses body heat to outside and thus cannot keep you as warm as woolens
- 14. 14.How does Solar heat reach the earth though the in between space is empty of matter? The heat from the sun comes through the electromagnetic radiation particularly in The IR wavelength and thus does not require any medium to travel
- 15. 15. What is convection? How can you demonstrate it to your buddy? Convection is the mode of transfer of heat in fluids
- 16. 16.What are lithosphere, hydrosphere and biosphere? Lithosphere is the solid part of the earth consisting of the crust and the upper mantle; Hydrosphere is the part of the earth covered by water and Biosphere is the entire globe consistIng of all forms of life starting from the bottom of the oceans upto the atmosphere.
- 17. 17. Explain the process of photosynthesis Photosynthesis is the process by which plants produce food by combining water,Carbon di oxide and nutrients by the action of sunlight six molecules of water plus six molecules of carbon di oxide produce one molecule of sugar plus six molecules of oxygen
- 18. 18. Why is the shade of a tree much cooler than the shade of a building? The shade of a tree is cooler because of the release of water vapour by the leaves during transpiration keeps the surrounding at lower temperature through the absorption of heat by water molecules
- 19. 19. Why are flowers colourful and sweet smelling? The colours and sweet smells of flowers is a natural device of the plants for attracting Insects like bees, butterflies and birds to sit on them and carry the pollen grains to other flowers of the same type for pollination
- 20. 20. What are the main roles of roots in plants? The main role of roots in a plant is to absorb water and other nutrients from the ground as also to give stable support to the plant
- 21. 21. What does one mean by electronic configuration? Explain with an example Electronic configuration defines the structure of atoms with the distribution of Electrons in their orbitals (shells) following the simple rule that there can be only 2n2 electrons in a given orbital with number n. For example if we consider the element Oxygen which has the atomic number 8, the electrons are so arranged that, there are 2 in the first shell and 6 in the second shell. Oxygen (2,6) Copper (2,8,18,1) Gold (2,8,18,32,18,1)
- 22. 22. What happens to an atom when it loses an electron? Atoms are always neutral, meaning the the number of positive charges (protons)should be equal to the number of negative charges (electrons). Hence if an atom looses an electron there will be a charge imbalance and the atom is said to be ionised and becomes a positive ion. Similarly when atom captures an electron then again the atom is ionised and this time it will become a negative ion
- 23. 23. What is the difference between a mixture and a compound? A mixture can be separated physically whereas a compound can be separated only chemically. A mixture will not have any molecular bonding, but a compound always has molecular bonding. A suspension of flour in water, Sodium Chloride crystal a heterogeneous mixture
- 24. 24. What happens when an acid reacts with a base? When acid reacts with a base the resultant products are a salt and water. Acids When acids dissolve in water they produce hydrogen ions, H+. For example, looking at hydrochloric acid: HCl(aq) -> H+(aq) + Cl-(aq) Alkalis When alkalis dissolve in water they produce hydroxide ions, OH-. For example, looking at sodium hydroxide: NaOH(aq) -> Na+(aq) + OH-(aq) Neutralisation reaction When the H+ ions from an acid react with the OH- ions from an alkali, a neutralisation reaction happens to form water. This is the equation for the reaction: H+(aq) + OH-(aq) ->H2O(l) If you look at the equations above for sodium hydroxide and hydrochloric acid you will see that there are Na+ ions and Cl- ions left over. These form sodium chloride, NaCl.
- 25. 25. Why do you have to add some salt to water to make it conduct electricity effectively? Pure water is a very poor conductor of electricity as the self ionisation of water is a very slow and ineffficient process. If we add a salt or some acid or base which are electrolytes water splits them into the positive and negative ion of the compound by breaking the ionic bond and these free ions can now conduct electrical current very well. Only then the seperation of water into hydrogen and oxygen becomes possible In the water at the negatively charged cathode, a reduction reaction takes place, with electrons (e−) from the cathode being given to hydrogen cations to form hydrogen gas: Cathode (reduction): 2H2O(l) + 2e− → H2(g) + 2OH−(aq); At the positively charged anode, an oxidation reaction occurs, generating oxygen gas and giving electrons to the anode to complete the circuit: Anode (oxidation): 2H2O(l) → O2(g) + 4H+(aq) + 4e−; Combining these two reactions yields the overall decomposition of water into oxygen and hydrogen: Overall reaction: 2H2O(l) → 2H2(g) + O2(g)
- 26. 26.A can finish some work in 6 days. If B is 50% more efficient than A in how many days will he finish the same work? In four days If the efficiency of A is 1 , that of B is 1 and half = 3/2 Time taken by B = 6 divided by 3/2 = 6 . 2/3 = 4
- 27. 27. In a class of 20 students, if 12 take French and 15 take German , how many are doing both? Seven Number of students taking other languages 12 + 15 = 27 As there are only 20 students 27 – 20 = 7 are taking both French and German
- 28. 28. If two apples and four pears together cost Rs 22, but a single apple is only Rs 5, what is the cost of a pear? Rs Three 2 A + 4 P = 22 , A =5 Therefore 10 + 4 P =22 which means 4P = 12. Hence P=3
- 29. 29. If Alistair loses 5 kgs weight and Ishan gains 5 kgs what happens to the average age of the two? Remains the same A=X I =Y Average = (X+Y)/2 A = X–5 I = Y+ 5 Average = (X+ 5 +Y -5)/2 = (X + Y) / 2
- 30. 30.In a right angled triangle if one of the angles is 350, what is the measure of the other angle? 550 A right angled triangle has one angle to be 900 Of the other two one is 350. Sum of the three angles of ANY triangle is 1800 Hence the measure of the third angle is 1800 – (900 + 350) = 550
- 31. 31. Which is the brightest natural object in the night sky? Planet VENUS
- 32. 32. Who invented the microscope? Leeuwenhoek was inspired by Anton Van Leeuwenhoek the glasses used by drapers to inspect the quality of cloth. He taught himself new methods for grinding and polishing tiny lenses of great curvature which gave magnifications up to 270x diameters, the finest known at that time. These lenses led to the building of Anton Van Leeuwenhoek's microscopes, and the biological discoveries for which he is famous. Anton Van Leeuwenhoek was the first to see and describe bacteria (1674), yeast plants, the teeming life in a drop of water, and the circulation of blood corpuscles in capillaries.
- 33. 33. What is sericulture? Sericulture is the practice of rearing silkworms For the production of raw silk. Silk-fibre is a protein produced from the silk-glands of silkworms. Historically, sericulture was introduced for the first time, into China by Hoshomin, the Queen of China. For a long time, sericulture was considered to be a national secret by the Chinese Government, and as an industry it was not known in other countries. Later, it was introduced into Europe and Japan as well. According to reports available, sericulture was introduced into India about 400 years back and the industry flourished as an agro-industry till 1857, with an annual production of two million pounds of silk fibre.
- 34. 34. What was CHIPKO movement? CHIPKO movement was the first active participation of villagers particularly the women against felling of trees by timbre contractors in the Himalyan region. As the name suggests, women hugged the trees when people came to axe them which indeed prevented the felling of trees. The first Chipko action took place spontaneously in April 1973 and over the next five years spread to many districts of the Himalaya in Uttar Pradesh. The Chipko protests in Uttar Pradesh achieved a major victory in 1980 with a 15-year ban on green felling in the Himalayan forests of that state by order of India's then Prime Minister, Indira Gandhi. Since then the movement has spread to various other parts of the country and generated pressure for a natural resource policy which is more sensitive to people's needs and ecological requirements. Prominent Chipko figures include: Sunderlal Bahuguna, a Gandhian activist who gave the Chipko slogan: 'ecology is permanent economy'. Chandi Prasad Bhatt, fostered locally-based industries based on the conservation and sustainable use of forest wealth for local benefit. Dhoom Singh Negi, who, with Bachni Devi and many village women, first saved trees by hugging them in the 'Chipko embrace'. They coined the slogan: 'What do the forests bear? soil, water and pure air'.
- 35. 35. Who was the first lady cosmonaut? Valentina Tereshkova On the morning of 16 June 1963, Tereshkova took off in Vostok 6 launched faultlessly, and she became the first woman to fly into space.Tereshkova orbited the earth 48 times and spent almost three days in space. Tereshkova also maintained a flight log and took photographs of the horizon, which were later used to identify aerosol layers within the atmosphere. It took 19 years until the second woman, Svetlana Savitskaya, flew into space in Soyuz-T-7 in 1982. The first US lady astronaut to go into space was Sally K.Ride in 1983,who went in Challenger STS -7
- 36. 36. Which is the largest living bird? Ostrich The Ostrich is a large flightless bird native to Africa (and formerly the Middle East). It is distinctive in its appearance, with a long neck and legs and the ability to run at speeds of about 65 km/h (40 mph). The Ostrich is the largest living species of bird and lays the largest egg of any bird species. The diet of the Ostrich mainly consists of seeds and other plant matter, though it eats insects. It lives in nomadic groups which contain between five and 50 birds. When threatened, the Ostrich will either hide itself by lying flat against the ground, or will run away. If cornered, it can cause injury and death with a kick from its powerful legs.
- 37. 37. what are parasites? Parasites are living organisms that live at the expense of some other living beings. They depend completely for their nourishment and sustenance on their host organism. IN plants the host range for most parasites is quite broad. However, a few are quite specific to a small group of related species. After seed germination, the radicle contacts a host root, and a holdfast is formed on the surface. A peglike root penetrates the host's root surface and grows into the water- and nutrient-conducting tissues, removing the materials needed for development. Common animal (human) parasites: roundworm, protozoan, bacterium, "Bear corn" parasite on oak roots fungus, yeast
- 38. 38. What is the main difference in the respiration of insects as against that of higher creatures? Respiration in insects is through a direct exchange of oxygen and carbon di oxide from the cells through pores in the skin and a system of tubular structures called trachea. Unlike the higher organisms they do not have lungs and further do not need the help of Circulation for carrying oxygen to different parts of their body. Air enters the insect's body through valve- like openings in the exoskeleton. These openings (called spiracles) are located laterally along the thorax and abdomen of most insects -- usually one pair of spiracles per body segment. Air flow is regulated by small muscles that operate one or two flap-like valves within each spiracle
- 39. 39. what is the main constituent of the human body? WATER Almost seventy percent of the Human body is made up of water. Mass of element Volume of Element in a 70-kg person purified element oxygen 43 kg 37 L carbon 16 kg 7.08 L hydrogen 7 kg 98.6 L nitrogen 1.8 kg 2.05 L calcium 1.0 kg 645 mL phosphorus 780 g 429 mL potassium 140 g 162 mL sulfur 140 g 67.6 mL sodium 100 g 103 mL chlorine 95 g 63 mL magnesium 19 g 10.9 mL iron 4.2 g 0.53 mL
- 40. 40. What are chromosomes? Chromosomes are organized structures of DNA and proteins that are found in cells. Chromosomes contain a single continuous piece of DNA, which contains many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions. The word chromosome comes from the Greek χρῶ μα (chroma, color) and σῶ μα (soma, body) due to their property of being stained very strongly by some dyes. Representation of the 23 paired chromosomes of the human male A very long DNA molecule and associated proteins, that carry portions of the hereditary information of an organism. The DNA molecule is highly condensed. The human DNA helix occupy too much space in the cell. Small proteins are responsible for packing the DNA into units called nucleosomes. Chromosomes are stained with A-T (G bands) and G-C (R bands) base pair specific dyes. When they are stained, the mitotic chromosomes have a banded structure that unambiguously identifies each chromosome of a karyotype. Each band contains millions of DNA nucleotide pairs.
- 41. 41.Can you give an example of a situation where Newton’s third law is applied? The simplest example is that of a jet engine. As the jet of burning gas is ejected from the rear, the plane moves forward due to the thrust provided by NTL As the wings push the air downwards As the chap fires, the escaping The air pushes the bird upwards. Bullet pushes the gun backwards In a recoil.
- 42. 42. Why are gaps provided in between the joints of railway lines? Heat expands solids. Hence in summer months the railway lines,made of steel would expand. To avoid jamming of lines sufficient gaps are provided. As all substances are made up of molecules, the space between molecules determine the state of matter as being solid liquid or gas. The arrangement of molecules is determined by their internal enegy. As heat is a form of energy when a substance is heated Its internal energy increases and thus the spacing between molecules increase leading to increase in volume that results in the expansion of the body.
- 43. 1. What is the difference between mass and weight of a body? Mass is the quantity of matter contained in a body whereas weight is the force acting on a body due to the acceleration due to gravity To measure the mass of a body one should use a common balance which has two pans hung from a beam so that the gravity acts on both the pans equally. On the other hand what one gets from a Spring balance is the weight of the body. Mass is expressed in units of ‘Kg’ while weight is expressed in ‘Newtons’
- 44. 44. What is the difference between fission energy and fusion energy? The binding energy released during the break up of radioactive heavy element, by Neutron bombardment is the Fission energy. The binding energy released when the light Elements (e.g. hydrogen) combines to formthe higher element (helium) is called the Fusion energy
- 45. 45. What are the constituents of air? The major constituents of AIR are N+O+Ar+CO2 = 99.98% Nitrogen N2 78.084% Oxygen O2 20.947% Argon Ar 0.934% Carbon Dioxide CO2 0.033% 18.2 parts per Neon Ne million 5.2 parts per Helium He million per 1.1 parts Krypton Kr million per Sulfur dioxide SO2 1.0 parts million per Methane CH4 2.0 parts million
- 46. 46. Give atleast three main differences between a plant cell and an animal cell Plant cell: cellwall-celulose a non living material, vacuole is larger in size, No organelles, and presence of green pigments called chloroplast. Animal cell: Vacuoles are smaller in number and size, no cell wall.
- 47. 47.what is Oesophagus? The oesophagus or food pipe is part of the digestive system. It is also sometimes called the gullet. It is the tube that carries food from your mouth to your stomach. It is about 26cm (10.5 inches) long in adults. As it passes through the chest, on its way to the stomach, it lies between the windpipe (trachea) and spinal cord.
- 48. 48. what is deceleration? Can you give an example when you find it useful? Deceleration is the opposite of acceleration. The rate of decrease of velocity with time is called deceleration. We use this while trying to bring a vehicle to stop.
- 49. 49. Give examples of some foods which are rich in vitamins A, C and D For vit A ; Spinach ,carrot, Butter, Mango For vit C : all fresh citrus fruits like lemon, orange For vit D : Oil ,Milk , cod liver oil
- 50. 50. What is the main function of red blood cells and where in human body the blood cells are produced? Main function of Red blood cells is to carry Oxygen to Different parts of the body. Blood cells are produced in the Bone marrow Bone marrow is the soft tissue found in the hollow interior of bones. and It constitutes approximately 4% of total body weight There are two types of bone marrow: red marrow (consisting mainly of myeloid tissue) and yellow marrow (consisting mainly of fat cells). Red blood cells, platelets and most white blood cells arise in red marrow; some white blood cells develop in yellow marrow