141. Rate of diffusion is

1. 1. Faster in solids than in liquids and gases

   
   
   

   2. Faster in gases than in solids and gases

   
   
   

   3. Faster in gases than in liquids and gases

   
   
   

   4. Equal in solids, liquids and gases

   
   
   

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   Correct Option: C

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142. A hollow sphere of radius R, a hollow cube of side R and thin circular plate of radius R made up of the same material, are all heated to 20°C above room temperature. When left to cool in the room, which of them will reach the room temperature first?

1. 1. Circular plate

   
   
   

   2. Cube

   
   
   

   3. Sphere

   
   
   

   4. All of them will reach the room temperature at the same time

   
   
   

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   Correct Option: C

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143. Woollen clothes keep the body warm because

1. 1. Wool increases the temperature of the body

   
   
   

   2. Wool is the bad conductor of the heat so it does not allow heat to flow out of the body

   
   
   

   3. Wool absorbs radiant heat from outer objects

   
   
   

   4. Wool rejects heat from outer objects

   
   
   

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   Correct Option: B

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144. In the winter season if we touch two blocks one of iron and another of wood in the early morning then the block of iron appears to be more cold because

1. 1. The temperature of the iron block is less than that of the wooden block

   
   
   

   2. Iron is a good conductor of heat in comparison of the wood

   
   
   

   3. Iron is a bad conductor of heat in comparison of the wood

   
   
   

   4. The block of iron is heavier than the wooden block

   
   
   

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   Correct Option: B

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145. 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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