171. Nights are cooler in the deserts than in the plains because

1. 1. Sand radiates heat more quickly than the earth

   
   
   

   2. The sky remains clear most of the time

   
   
   

   3. Sand absorbs heat more quickly than the earth

   
   
   

   4. Of none of the above reasons

   
   
   

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   Correct Option: A

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172. While measuring the thermal conductivity of a liquid, we keep the upper part hot and the lower part cool because

1. 1. Heat conduction is easier downwards

   
   
   

   2. Convection gets stopped in this way

   
   
   

   3. Radiation gets stopped in this way

   
   
   

   4. It is easier and more convenient to do so

   
   
   

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   Correct Option: B

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173. Heat capacity of substance is infinite. It means

1. 1. Infinite heat is given out

   
   
   

   2. Infinite heat is taken in

   
   
   

   3. No change in temperature whether heat is taken in or give out

   
   
   

   4. All of the above

   
   
   

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   N/A

   Correct Option: C

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174. The critical temperature of a gas is the temperature

1. 1. At which Boyle's law is strictly obeyed

   
   
   

   2. At which the gas liquefies at a pressure of one atmosphere

   
   
   

   3. Above which the gas cannot be liquefied

   
   
   

   4. Below which the gas cannot be liquefied

   
   
   

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   Correct Option: C

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175. The unit of temperature adopted by the SI (international system of units) is the celsius and kelvin scales. It is based on the

1. 1. Melting point of ice

   
   
   

   2. Boiling point of water

   
   
   

   3. Triple point of water corresponding to -0.01°C

   
   
   

   4. Temperature at which solid, liquid and gaseous water are all in equilibrium, i.e., -273°C

   
   
   

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   Correct Option: C

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