CBSE
Multiple Choice QuestionsWhen a current is passed in a conductor, 5°C rise in temperature is observed. If the strength of current is made thrice, rise in temperature will be
5 oC
20 oC
45 oC
15 oC
Assertion: A piece of ice, with a stone frozen inside it, floats on water in a beaker. When the ice melts, the level of water in the beaker decreases.
Reason: Density ofstone is more than that of water.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false.
If both assertion and reason are false.
If 10goficeis added to 40 g of water at 15°C, then the temperature of the mixture is(specific heat of water = 4.2 x 103 J kg-1K-1, Latent heat of fusion of ice = 3.36 x 105 J kg-1 )
15 oC
12 oC
10 oC
0 oC
Two chambers containing m1 g and m2 g of a gas at pressures P1 and P2 respectively are put in communication with each other, temperature remaining constant. The common pressure reached will be
Assertion: Current is passed through a metallic wire so that it becomes red hot. When cold water is poured on half of its portion, the rest of the half portion becomes more hot.
Reason: Resistance decreases due to decrease in temperature.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
The temperature of a body is increased from 73o C to 327o C. Then the ratio of emissive power is
1/9
1/27
27
81
Assertion: A hollow metallic closed container with small opening maintained at a high temperature can act as a source of black body radiation.
Reason: All metals act as black body radiator.
If both assertion and reason are true and reason is the correct explanation of assertion.
If both assertion and reason are true but reason is not the correct explanation of assertion.
If assertion is true but reason is false.
If both assertion and reason are false.
A copper ball 2 cm in radius is heated in a furnace to 327 °C. If its emissivity is 0.3, at what rate does it radiate energy?
1.72 W
2.73 W
11.0 W
2.15 W
70 calories of heat are required to raise the temperature of 2 moles of an ideal gas at constant pressure from 30°C to 35°C. The amount of heat required to raise the temperature of the same sample of the gas increases with through the same range at constant volume is (Gas constant= 1·99 cal/K-mole)
30 cal
50 cal
70 cal
90 cal
higher than 0°C
higher than 0 K
higher than that of its surroundings
high enough for it to glow
