66. During melting process the heat given to a body is utilised in

1. 1. Increasing the temperature

   
   
   

   2. Increasing the density of the material

   
   
   

   3. Increasing the potential energy of the molecules

   
   
   

   4. Increasing the kinetic energy of the molecules

   
   
   

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   N/A

   Correct Option: C

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67. Which one of the following statements is correct. Transfer of heat energy from a heater coil to the cooking vessel takes place through the process of

1. 1. Convection only

   
   
   

   2. Conduction and convection only

   
   
   

   3. Radiation and convection only

   
   
   

   4. Convection, conduction and radiation

   
   
   

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   N/A

   Correct Option: C

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68. Pressure exerted by gas is

1. 1. Independent of the density of the gas

   
   
   

   2. Inversely proportional to the density of the gas

   
   
   

   3. Directly proportional to the density of the gas

   
   
   

   4. Directly proportional to the square of the density of the gas

   
   
   

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   N/A

   Correct Option: C

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69. The specific heat of a gas at constant pressure is greater than the specific heat at constant volume because

1. 1. Work is done in the expansion of the gas at constant pressure

   
   
   

   2. Work is done in the expansion of the gas at constant volume

   
   
   

   3. The attraction between the molecules increases at constant pressure

   
   
   

   4. The molecular collision increases at constant pressure

   
   
   

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   Correct Option: A

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70. An electric heater, kept in vacuum, is heated continuously by passing electric current. Its temperature

1. 1. Will go on rising with time

   
   
   

   2. Will stop rising after some time as it will lose heat to the surrounding by conduction

   
   
   

   3. Will become constant after some time because of loss of heat due to radiation

   
   
   

   4. None of the above

   
   
   

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   Correct Option: C

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