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Heat

179 MCQ questions with answers and explanations · page 3 of 8

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Q51. Why do pendulum clocks become slow in summer?

  1. ABecause of the long summer days
  2. Bdue to friction in the coil
  3. CThe length of the pendulum increases, which increases the time taken for a single oscillation.
  4. DThe weight of the pendulum increases in summer
Show answer & explanation

Answer: C) The length of the pendulum increases, which increases the time taken for a single oscillation.

Q52. A solid metal ball has a cavity inside it. When this metal ball is heated, the volume of the cavity will

  1. Awill increase
  2. Bwill decrease
  3. Cdo not very
  4. Dwill be doubled
Show answer & explanation

Answer: A) will increase

Q53. When water is filled in a bottle and allowed to freeze, the bottle breaks because-

  1. Awater expands when it freezes
  2. BThe bottle contracts at freezing point.
  3. CThe temperature outside the bottle is higher than inside.
  4. Dwater expands when heated
Show answer & explanation

Answer: A) water expands when it freezes

Q54. Water pipelines in the mountains burst during extreme winter. This is because:

  1. AThe pipe shrinks due to cold.
  2. BWater in pipes shrinks when it freezes
  3. CWater in pipes expands when it freezes
  4. DPipes expand as they cool
Show answer & explanation

Answer: C) Water in pipes expands when it freezes

Q55. Why is a small space left at the junction of two railway tracks?

  1. ABecause leaving such places will save some costs.
  2. BBecause metal expands when heated and contracts when cooled
  3. Cto generate the necessary gravitational force
  4. Dnone of these
Show answer & explanation

Answer: B) Because metal expands when heated and contracts when cooled

Q56. The water on the surface of a lake is just about to freeze. What will be the temperature of the water at the bottom of the lake?

  1. A0°C
  2. B1°C
  3. C2°C
  4. D4°C
Show answer & explanation

Answer: D) 4°C

Q57. In winter, when water freezes due to cold, then fish and other aquatic creatures-

  1. ACan survive because only the top layer of water freezes
  2. Bmove to other warmer places
  3. Ccan survive safely because they have an innate ability to tolerate cold
  4. Ddies
Show answer & explanation

Answer: A) Can survive because only the top layer of water freezes

Q58. The method of transmission of heat is-

  1. AConduction
  2. BConvection
  3. CRadiation
  4. DAll of the above
Show answer & explanation

Answer: D) All of the above

Q59. In which method of heat transfer do the molecules of the substance not move from one place to another on their own?

  1. Aconduction
  2. Bconvection
  3. Cradiation
  4. DAll three
Show answer & explanation

Answer: A) conduction

Q60. Heat transfer in liquids and gases takes place by which of the following methods?

  1. Aconduction
  2. Bconvection
  3. Cradiation
  4. Dall of which
Show answer & explanation

Answer: B) convection

Q61. Water is heated in an electric kettle by-

  1. ACauses of conduction
  2. Bdue to convection
  3. Cdue to radiation
  4. Dall of which
Show answer & explanation

Answer: B) due to convection

Q62. The Sun's heat reaches the Earth through which of the following types of transmission medium?

  1. Aconvection
  2. Bradiation
  3. CSannayan
  4. Dheat exchange
Show answer & explanation

Answer: B) radiation

Q63. In which method of heat transfer medium is not necessary?

  1. Aconduction
  2. Bconvection
  3. Cradiation
  4. Dall of which
Show answer & explanation

Answer: C) radiation

Q64. Which is the method of heat transfer in which the particles of the medium do not move?

  1. Aconduction
  2. Bconvection
  3. Cradiation
  4. Dall of which
Show answer & explanation

Answer: C) radiation

Q65. Which of the following is the best conductor of heat?

  1. AWater
  2. BMercury
  3. CWood
  4. Dleather
Show answer & explanation

Answer: B) Mercury

Q66. The thermal conductivity of silver is higher than that of copper.

  1. Aare less
  2. Bis more
  3. Cis equal to
  4. Dnone of these
Show answer & explanation

Answer: B) is more

Q67. Bolometer is a device for measuring—

  1. Aof pressure
  2. Bgrowth in plants
  3. Cof thermal radiation
  4. Dof wind speed
Show answer & explanation

Answer: C) of thermal radiation

Q68. If you touch an iron block and a wooden block in the morning during cold days, the iron block feels colder because-

  1. AThe temperature of an iron block is lower than that of a wooden block
  2. BIron is a better conductor of heat than wood
  3. CIron is a poor conductor of heat compared to wood.
  4. DIron block is heavier than wood
Show answer & explanation

Answer: B) Iron is a better conductor of heat than wood

Q69. During harsh winters, the surface of a lake freezes, but the water at its bottom remains liquid. What causes this?

  1. AIce is a bad conductor of heat
  2. BThere is no heat loss because the temperature of the lake surface and the air is the same.
  3. CThe density of water is maximum at 4°C.
  4. DNone of the above statements is correct in this context
Show answer & explanation

Answer: C) The density of water is maximum at 4°C.

Q70. When a table fan is run in a closed room, the air in the room-

  1. Ait will be hot
  2. Bit will be cold
  3. Cwill have no effect
  4. Dnone of the above
Show answer & explanation

Answer: A) it will be hot

Q71. If the door of the refrigerator kept in the room is left open-

  1. AThe room will cool down to the temperature inside the refrigerator.
  2. BThe room will cool to a temperature higher than the inside of the refrigerator
  3. CThe room will gradually heat up
  4. DThe temperature of the air in the room will remain unchanged.
Show answer & explanation

Answer: C) The room will gradually heat up

Q72. If a metal is used to make cooking utensils, then the heat conductivity-

  1. Ashould be less
  2. BThere should be more
  3. CElectrical conductivity should be low
  4. DThe density should be high
Show answer & explanation

Answer: A) should be less

Q73. Which of the following is the best conductor of heat?

  1. Acold water
  2. Bhot water
  3. Csea water
  4. Ddistilled water
Show answer & explanation

Answer: C) sea water

Q74. What is the transfer of heat through molecular structure called?

  1. Aconduction
  2. Bconvection
  3. Cradiation
  4. Dscattering
Show answer & explanation

Answer: B) convection

Q75. Which of the following liquids is a very good conductor of heat?

  1. AMercury
  2. BWater
  3. CEther
  4. Dbenzene
Show answer & explanation

Answer: A) Mercury

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