CBSE
Multiple Choice QuestionsConsider two containers P and Q containing identical gases at same temperature, pressure and volume. The gas in container P is compressed to half of its original volume isothermally while the gas in container Q is compressed to half of its original value adibatically. The ratio of final pressure of gas is
A refrigerator is driven by 1000 W electric motor having an efficiency of 60%. The refrigerator is considered as a reversible heat engine operating between 273 K and 303 K. Time required by it to freeze 32.5 kg of water at 0°C is. (Given, latent heat of fusion of ice = 336 × 103 J-kg-1 and heat lost may be neglected).
53 min 20 s
33 min 20 s
48 min 40 s
28 min 32 s
Work of 146 kJ is performed in order to compress one kilo mole of a gas adiabatically and in this process the temperature ofthe gas increases by 7° C. The gas is (R = 8.3 J mol-1 K-1 )
diatomic
triatomic
a mixture of monoatomic and diatomic
monoatomic
Consider an ideal gas confined in an isolated closed chamber. As the gas undergoes an adiabatic expansion, the average time of collision between molecules increases to Vq , where V is the volume of the gas. The value of q is
An ideal heat engine exhausting heat at 27° C is to have 25% efficiency. It must take heat at
127 °C
227° C
327° C
None of these
Two spherical soap bubbles of radii r1 and r2 in vacuum combine under isothermal conditions. The resulting bubble has a radius equal to
The pressure and density of a diatomic gas change adiabatically from (P1 , ρ1) to (P2 , ρ2) . If , then should be
16
32
64
128
One mole of an ideal gas at an initial temperature of T K does 6R joules of work adiabatically. If the ratio of specific heats of this gas at constant pressure and at constant volume is 5/3, then final temperature of the gas will be
(T − 4) K
(T + 4) K
(T − 2.4)K
(T + 2.4) K
According to first law of thermodynamics
energy is conserved
mass is conserved
heat is constant in isothermal process
heat neither enters nor leaves system
Ten moles of an ideal gas at constant temperature 500 K is compressed from 50 L to 5 L. Work done in the process is (Given, R = 8.31 J-mol-1 - K-1 )
- 1.2 x 104 J
- 2.4 x 104 J
- 4.8 x 104 J
- 9.6 x 104 J
