64. Clear nights are colder than cloudy nights because of?
A.Conduction
B.Condensation
C.Radiation
D.Insolation
65. Speed of sound is the greatest in :(I) Water
A.water
B.Air
C.Glass
D.Glycerin
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?
A.Pyrex glass
B.Flint glass
C.Crooks glass
D.Crystal glass
68. The speed of light with the rise in the temperature of the medium:
A.Increases
B.Decreases
C.Remains unaltered
D.Drops suddenly
69. Clothes keep us warm in winter because they :
A.Supply heat
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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