Thermodynamics: JEE Main Physics Previous Year Questions

484 previous year questions from Thermodynamics. Here are the 25 most important ones; open any question for the correct answer and a full step-by-step solution.

1. $A body cool from 70^{\circ} C to 40^{\circ} C in 5 min . Calculate the time it takes to cool from 60^{\circ} C to 40^{\circ} C . The temperatur\dots$
2. $Find the difference in temperature between the water at the top and the bottom of 20 m high waterfall assuming 10 % of the energy of fall is spent in h\dots$
3. $If for a gas, \frac{R}{C _{V}} = 0.67, this gas is made up of molecules which are$
4. $A body cools from 60°C to 40°C in 6 minutes. If, temperature of surroundings is 10°C. Then, after the next 6 minutes, its temperature will be____°C.$
5. $A carnot engine has the same efficiency between 800 K to 500 K and x K to 600 K. The value of x is$
6. $The efficiency of Carnot's heat engine is 0.5 when the temperature of the source is T_{1} and that of sink is T_{2} . The efficiency of another Carnot's heat eng\dots$
7. $The work done in an adiabatic change in an ideal gas depends upon only:$
8. $Let γ_{1} be the ratio of molar specific heat at constant pressure and molar specific heat at constant volume of a monoatomic gas and γ_{2} be the s\dots$
9. $Which of the following statements is NOT true?$
10. $The efficiency of a Carnot engine operating with reservoir temperature of 10 0^{o} Cand - 2 3^{o} C will be$
11. $The coefficient of performance of a Carnot refrigerator working between 3 0^{o} C and 0^{o} C is$
12. $The pressure and volume of an ideal gas are related as PV^{3/2} = K (Constant). The work done by gas when the gas is taken from state\dots$
13. $Even Carnot engine cannot give 100% efficiency because we cannot$
14. $A Carnot engine operates between a source and a sink. The efficiency of the engine is 40 % and the temperature of the sink is 27^{\circ} C . If the efficien\dots$
15. $The change in internal energy when 20 g of a gas is heated from 25^{\circ} C to 35^{\circ} C at constant volume is (Specific heat capacity of the gas at const\dots$
16. $A diatomic gas, having C_{p} = \frac{7}{2} R and C_{v} = \frac{5}{2} R, is heated at constant pressure. The ratio dU : dQ : dW$
17. $If Δ U and Δ W represent the increase in internal energy and work done by the system respectively in a thermodynamical process, which of the following is\dots$
18. $The efficiency of Carnot engine is 50% and temperature of sink is 500 K. If the temperature of source is kept constant and its efficiency is to be raised to 60%; then the\dots$
19. $The surface of a black body is at a temperature 727^{\circ} C and its cross-section is 1 m^{2} . Heat radiated from this surface in one minute in joules is (Stefa\dots$
20. $Under an adiabatic process, the volume of an ideal gas gets doubled. Consequently the mean collision time between the gas molecules changes from τ_{1} to\dots$
21. $An ideal Carnot engine whose efficiency is 50 % receives heat at 500 K . If the efficiency is to be 60 %, then intake temperature for the same\dots$
22. $A heat engine has an efficiency of (\frac{1}{6}) . When the temperature of sink is reduced by 6 2^{0} C, its efficiency get doubled. The temperature of th\dots$
23. $Molecules of an ideal gas are known to have three translational degrees of freedom and two rotational degrees of freedom. The gas is maintained at a temperature of T .\dots$
24. $A gas is kept in a container having walls which are thermally non-conducting. Initially the gas has a volume of 800 cm^{3} and temperature\dots$
25. $A number of Carnot engines are operated at identical cold reservoir temperatures (T_{L}) . However, their hot reservoir temperatures are kept different. A\dots$

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Thermodynamics: JEE Main Physics Previous Year Questions

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