Question 1. The mass of a body is different from its weight because________
Answer: mass is a measure of the quantity of matter whereas weight is a force
Question 2. Let WP and WE be the weights of a body at the north pole and at the equator respectively. If the earth were not rotating then WP ________
Answer: would remain unchanged
Question 3. A person weighs more in a lift, which is________
Answer: accelerating upward
Question 4. A ball tied with a string to a rotating shaft revolves at uniform speed. As the shaft is suddenly brought to rest the string starts getting round the shaft with the angular velocity of the ball________
Answer: increasing
Question 5. One finds it more difficult to walk on ice than on a concrete road because________
Answer: the friction between the ice and the feet is less than that between the concrete and the feet
Question 6. It is easier to roll a barrel than to pull it because________
Answer: rolling friction is much less than sliding friction
Question 7. A sheet of paper can be pulled out quickly from under a glass of water without spilling the water. This phenomenon illustrates________
Answer: inertia
Question 8. A horse pulling a tanga moves forward due to the force exerted by________
Answer: the ground on the horse’s feet
Question 9. When the velocity of a body is doubled, its momentum is________
Answer: doubled
Question 10. The work done in holding a weight of 20 kg at a height of 1 m above the ground is________
Answer: zero
Question 11. Ther Universal Law of Gravitation was propounded by________
Answer: Newton
Question 12. Winding a watch is actually the process of storing________
Answer: potential energy
Question 13. Conservation of energy means that________
Answer: energy can neither be created nor
Question 14. The period of revolution of a geostationary satellite is________
Answer: 24 hours
Question 15. If an apple is released from an orbiting spaceship, it will move________
Answer: along with the spaceship at the same speed
Question 16. A steel ball floats on mercury because________
Answer: the density of mercury is higher than that of steel
Question 17. The atmosphere exerts enormous pressure on us. But we do not feel it because________
Answer: our blood exerts a pressure slightly more than that of the atmosphere
Question 18. In a barometer, mercury is preferred over water because________
Answer: mercury has high density and low vapour pressue
Question 19. A stone is thrown into a deep lake. As it sinks deeper and deeper into the water, the upthrust acting on it________
Answer: remains constant
Question 20. Raindrops are spherical due to________
Answer: surface tension
Question 21. On a clean glass plate a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because________
Answer: cohesion of mercury is greater than its adhesion with glass
Question 22. The swing of a spinning cricket ball in the air can be explained on the basis of________
Answer: Bernoulli’s theorem
Question 23. In a sprayer the liquid rises in the tube due to________
Answer: lower pressure at the upper end
Question 24. A football bounces when it falls on the ground because________
Answer: of its property of elasticity
Question 25. The science dealing with the study of phenomena at very low temperatures is known as________
Answer: Cryogenics
Question 26. In cold countries alcohol is preferred to mercury as a thermometric liquid because________
Answer: Alcohol has a very low freezing point
Question 27. When a certain mass of liquid is heated in a glass flask the liquid level________
Answer: Falls at fir st and then starts rising
Question 28. When a cube of ice floating on water in a beaker melts, the level of water in the beaker________
Answer: Remains the same
Question 29. If water in a lake were to behave like other liquids, then in extremely cold weather it would freeze________
Answer: from bottom to top
Question 30. The tem perature of the t op of a frozen lake is________15°C. What is the temperature of the water in the lake in contact with the ice layer?
Answer: 0°C
Question 31. Fish can survive inside a frozen lake because________
Answer: water near the bottom does not freeze
Question 32. When w ater is c ooled fr om 8°C t o 0°C its volume________
Answer: decreases up to 4° C and then increases
Question 33. The best conductor of heat among liquids is________
Answer: mercury
Question 34. A thermostat is a device for________
Answer: regulating temperature
Question 35. Using the codes GH for good conductor of heat, BH for bad conductor of heat, GE for good conductor of electricity and BE for bad conductor of electricity, mica can be classified as:
Answer: GH and BE
Question 36. A pyrex tumbler does not crack when hot water is poured into it because pyrex________
Answer: does not expand much on heating
Question 37. The freezer in a refrigerator is fitted near the top________
Answer: so that it can cool the whole interior by setting up convection currents
Question 38. By what process is heat transmitted from the filament of an evacuated electric bulb of the glass________?
Answer: radiation
Question 39. Hot coffee is poured simultaneously in four metallic tumblers painted outside with different types of paints. After some time, the coffee will be found coldest in the tumbler painted________
Answer: rough black
Question 40. Light coloured clothes are preferred in summer because________
Answer: light colours are poor absorbers of heat
Question 41. By which methods could a cup of hot coffee lose heat if placed on a metal table in a room________
Answer: conducti on, convec -tion, radiation and evaporation
Question 42. In a cup, tea cools from 99°C to 80°C in exactly one minute. It will cool from 70°C to 60°C in________
Answer: more than one minute
Question 43. A little ether on the palm gives a cooling sensation because ether________
Answer: evaporates
Question 44. Scalding with steam is more severe than scalding by boilding water because________
Answer: Steam contai ns more energy than boiling water
Question 45. One feels cold after a dip in sea water due to________
Answer: the evaporation of water on the body
Question 46. The surface of water in a pond remains cool even on a hot day because________
Answer: water evaporates at the surface and evaporation cause cooling
Question 47. The boiling point of water depends on________
Answer: atmospheric pressure
Question 48. The cover of a solar cooker is made of glass because________
Answer: because glass allows sunlight into the container but does not allow heat radiation out of it
Question 49. Light waves are different from sound waves in that________
Answer: light waves are electromagnetic but sound waves are not
Question 50. Delhi radio station broadcasts at a frequency of 819 kHz. What is the wavelength of the radio-waves?
Answer: 3.66 x 102 m
146 videos|358 docs|249 tests
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2. How is energy involved in chemical reactions? |
3. What are enzymes and how do they influence chemical reactions in living organisms? |
4. What are the main factors that can influence the rate of a chemical reaction? |
5. How do acids and bases affect chemical reactions? |
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