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Heat

179 MCQ questions with answers and explanations · page 4 of 8

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Q76. Which part of the solar radiation heats the solar cooker?

  1. Aultraviolet rays
  2. Binfrared rays
  3. Ccosmic ray
  4. Doptical beam
Show answer & explanation

Answer: B) infrared rays

Q77. Clothes keep us warm in winter because-

  1. Aprovide heat
  2. BDoes not radiate heat.
  3. CPrevents air from coming into contact with the body
  4. DPrevents body heat from escaping
Show answer & explanation

Answer: D) Prevents body heat from escaping

Q78. Which of the following is the most appropriate colour combination for an umbrella to protect from the sun?

  1. Ablack on top white on bottom
  2. Bwhite on top black on bottom
  3. CBlack top and bottom
  4. DWhite top and bottom
Show answer & explanation

Answer: B) white on top black on bottom

Q79. Black skinned people from Africa compared to white skinned people from Britain-

  1. Afeel more heat
  2. Bfeel less heat
  3. Cfeel the same heat
  4. DDo not feel the heat
Show answer & explanation

Answer: A) feel more heat

Q80. The morning sun is not as hot as the afternoon sun because-

  1. AThe sun's rays move slowly in the morning.
  2. BThe sun is cold in the morning.
  3. CThe Earth is farther from the Sun in the morning
  4. DIn the morning, the sun's rays have to travel a greater distance in space.
Show answer & explanation

Answer: D) In the morning, the sun's rays have to travel a greater distance in space.

Q81. Why are white clothes cooler than black clothes?

  1. Aabsorb all light that reaches them
  2. BThey reflect whatever light reaches them.
  3. Cdoes not allow light to penetrate
  4. DCompletely cools the sunlight
Show answer & explanation

Answer: B) They reflect whatever light reaches them.

Q82. Woolen clothes are warmer than cotton clothes because they-

  1. Aare good heat absorbers
  2. Bare good heat distributors
  3. Care heavier than cotton clothes
  4. Dare good heat insulators
Show answer & explanation

Answer: D) are good heat insulators

Q83. Steam burns are more painful (serious) than boiling water burns.

  1. ASteam has latent heat,
  2. BSteam is a type of gas and it immerses the body quickly.
  3. CSteam easily enters the body through the pores present in the body.
  4. DSteam has a very high temperature
Show answer & explanation

Answer: A) Steam has latent heat,

Q84. The presence of moisture in the atmosphere is ascertained by observing water droplets on the outer surface of a steel glass filled with-

  1. Awith warm milk
  2. Bwith hot water
  3. Cwith cold water
  4. Dfrom normal water
Show answer & explanation

Answer: C) with cold water

Q85. “Good emitters are good absorbers.” This is the law—

  1. AKirchhoff's law
  2. BStefan's law
  3. CNewton's law of cooling
  4. Dlaw of thermodynamics
Show answer & explanation

Answer: A) Kirchhoff's law

Q86. The radiant energy emitted per second from a unit surface area of a black body is directly proportional to the fourth part of its absolute temperature. This law is:

  1. ANewton's law of cooling
  2. BKirchhoff's law
  3. CStefan's law
  4. Dlaw of thermodynamics
Show answer & explanation

Answer: C) Stefan's law

Q87. Stefan's law of radiation is-

  1. AE∝1/T4
  2. BE∝T2
  3. CE∝T4
  4. DE∝1/T2
Show answer & explanation

Answer: C) E∝T4

Q88. The rate at which an object cools is directly proportional to the temperature difference between the object and the medium surrounding it. This law is:

  1. ANewton's law of cooling
  2. BStefan's radiation law
  3. CKirchhoff's law
  4. Dzero point law of thermodynamics
Show answer & explanation

Answer: A) Newton's law of cooling

Q89. Newton's law of cooling is applicable only when-

  1. AThe temperature difference should not be too great
  2. BThe temperature difference is too great
  3. Cdoes not depend on temperature difference
  4. Dnone of these
Show answer & explanation

Answer: A) The temperature difference should not be too great

Q90. Hot water takes 10 minutes to cool from 90°C to 80°C, then it will take time to cool from 80°C to 70°C-

  1. A10 minutes
  2. BLess than 10 minutes
  3. Cmore than 10 minutes
  4. DNot sure
Show answer & explanation

Answer: C) more than 10 minutes

Q91. The inventor of Thermos Flask is-

  1. ADivar
  2. BStephen
  3. CKirchhoff
  4. DNewton
Show answer & explanation

Answer: A) Divar

Q92. The liquid in a thermos flask remains hot or cold for a long time because there is no loss or gain of heat.

  1. AOperation
  2. Bconvection and radiation
  3. Cboth a and B
  4. DNone of these
Show answer & explanation

Answer: C) both a and B

Q93. The inner walls of the Dharmas flask are shiny.

  1. ATo prevent heat loss by convection
  2. BTo prevent heat loss by radiation
  3. CTo prevent heat loss by conduction
  4. DNone of these
Show answer & explanation

Answer: B) To prevent heat loss by radiation

Q94. Thermos flask keeps liquids hot for a long time because-

  1. AIt is filled with gas that emits heat.
  2. BThere is internal heating in it.
  3. CDouble walls of radiant inner wall and outer cladding prevent heat from escaping or entering
  4. Dnone of the above
Show answer & explanation

Answer: C) Double walls of radiant inner wall and outer cladding prevent heat from escaping or entering

Q95. By which method are the walls of a thermos flask coated to minimize heat transfer?

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

Answer: C) radiation

Q96. The heat required to raise the temperature of a unit mass of a substance by one degree Celsius is-

  1. Aspecific heat
  2. Bheat capacity
  3. Cwater equivalent
  4. Dlatent heat
Show answer & explanation

Answer: A) specific heat

Q97. Which of the following has the highest value of specific heat?

  1. Aglass
  2. BCopper
  3. Clead
  4. DWater
Show answer & explanation

Answer: D) Water

Q98. During the day, the earth heats up much faster than the sea water because-

  1. AThe density of the Earth is greater than that of water
  2. BDue to aquatic animals living in the sea
  3. CThe specific heat capacity of water is very high
  4. Dwater is made up of hydrogen and oxygen
Show answer & explanation

Answer: C) The specific heat capacity of water is very high

Q99. Water is used to cool the radiator of an automobile because-

  1. Awater has a high specific heat
  2. Bthe density of water is low
  3. CWater is cheap
  4. DWater is available at low temperature.
Show answer & explanation

Answer: A) water has a high specific heat

Q100. Cryogenic engines are used in-

  1. AIn submarine propulsion
  2. Bin frost-free refrigerators
  3. Cin rocket technology
  4. Din research on superconductivity
Show answer & explanation

Answer: C) in rocket technology

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