Multiple Choice QuestionsA wire is stretched under a force. If the wire suddenly snaps the temperature of the wire
remains the same
decrease
increase
first decrease then increase
When the room temperature becomes equal to the dew point, the relative humidity of the room is
100 %
zero %
70 %
85 %
Two rods of equal length and diameter have thermal conductivities 3 and 4 units respectively. If they are joined in series, the thermal conductivity of the combination would be
3.43
3.5
3.4
3.34
19 g of water at 30°C and 5 g of ice at -20°C are mixed together in a calorimeter. What is the final temperature of the mixture ? (Given specific heat of ice = 0.5 cal g-1 (C)-1 and latent heat of fusion of ice = 80 cal g-1)
0°C
− 5°C
5°C
10°C
It is difficult to cook rice in an open vessel by boiling it at high altitudes because of
low boiling point and high pressure
high boiling point and low pressure
low boiling point and low pressure
high boiling point and high pressure
The height of a waterfall is 50 m. If g = 9.8 ms-2 the difference between the temperature at the top and the bottom of the waterfall is
1.17°C
2.17°C
0.117°C
1.43°C
Experimental investigations show that the intensity of solar radiation is maximum for a wavelength 480 nm in the visible region. Estimate the surface temperature of sun. (Given Wien's constant b = 2.88 x 10-3 mK.)
4000 K
6000 K
8000 K
106 K
The temperature of an ideal gas is increased from 120 K to 480 K. If at 120 K, the root mean square speed of gas molecules is v, then at 480 K, it will be
4v
2v
A block of ice at temperature -20°C is slowly heated and converted to steam at 100°C. Which of the following diagram is most appropriate ?
A.
The ice at -20° C converts to ice at 0° C, thus having an increase in temperature. On further heating, ice at 0°C is converted into water at 0°C, thus the temperature remaining constant, a change of phase occurs. Water at 0°C when heated changes to water at 100°C, thus resulting in an increase of temperature. Water at 100°C changes to steam at 100°C, thus resulting in a change of phase. Hence, Fig. (A) is the correct answer.
Two black bodies at temperatures 327°C and 427°C are kept in an evacuated chamber at 27°C. The ratio of their rates of loss of heat are
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