64. Clear nights are colder than cloudy nights because of?
65. Speed of sound is the greatest in :(I) Water
66. A gas thermometer is more sensitive than a liquid thermometer because a gas:
A.is lighter than liquid
B.Expands more than a liquid
C.Is easy to obtain
D.Does not change state easily
67. Which one of the following is used for sun glasses?
68. The speed of light with the rise in the temperature of the medium:
69. Clothes keep us warm in winter because they :
B.Do not radiate heat
C.Prevent air from contacting the body
D.Prevent the heat of the body from escaping
70. In a refrigerator what produces the cooling ?
A.The ice which deposits on the freezer
B.The sudden expansion of a compressed gas
C.The evaporation of a volatile liquid
D.None of these
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