76. A glass container cracks when very hot tea is poured into it. A probable reason for this is the

1. 1. Low thermal conductivity of glass

   
   
   

   2. High thermal conductivity of glass

   
   
   

   3. Low specific heat of glass

   
   
   

   4. None of the above

   
   
   

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   N/A

   Correct Option: A

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77. A solid sphere of radius R and a hollow sphere of inner radius R / 2 and outer radius R, made of copper, are heated to the same temperature and are allowed to cool in the same environment. Then

1. 1. Hollow sphere cools faster

   
   
   

   2. Both the spheres attain room temperature at the same time

   
   
   

   3. Solid sphere cools faster

   
   
   

   4. None of the above

   
   
   

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   N/A

   Correct Option: A

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78. A solid cube and solid sphere of the same material have equal surface areas. Both are at the same temperature of 120° C then

1. 1. Both of them will cool down at the same rate

   
   
   

   2. The cube will cool down faster than the sphere

   
   
   

   3. The sphere will cool down faster than the cube

   
   
   

   4. None of the above

   
   
   

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   N/A

   Correct Option: B

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79. It is difficult to cook at high altitudes because

1. 1. There is less oxygen in the air

   
   
   

   2. Due to falling temperature, more heat has to be given

   
   
   

   3. Due to decrease in atmospheric pressure, the boiling point of water decreases

   
   
   

   4. Of high moisture content there

   
   
   

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   N/A

   Correct Option: C

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80. 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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1. View Hint View Answer Discuss in Forum

   N/A

   Correct Option: C

   N/A

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