Thermodynamics Mock Test – Class 11 Physics

1. A thermodynamic process is reversible only if both the system and surroundings can be restored to their initial states. Which situation most clearly prevents this?

2. A heat engine has in each cycle. Its efficiency is

3. Consider the following statements about thermodynamic equilibrium.
I. Thermal equilibrium requires no temperature gradient.
II. Mechanical equilibrium requires no unbalanced pressure difference causing macroscopic motion.
III. Complete thermodynamic equilibrium can exist even while the system is undergoing a visible chemical reaction.

4. The product uses pressure in and volume change in . Its unit reduces to ______.

5. Read the passage and answer the question.

What must be the same for the two processes?

6. A reversible refrigerator and a reversible heat engine are both operated between and . The refrigerator COP and engine efficiency are respectively

7. A reversible adiabatic compression changes the pressure of an ideal gas from to . If , the ratio is

8. A thermodynamic state variable is a quantity that

9. A complete thermodynamics summary table is being checked. Which row contains only correct associations?

10. A learner says, “A hot body contains a large amount of heat.” The most suitable thermodynamic response is:

11. A student says, “The adiabatic steps in a Carnot cycle are useless because no heat is transferred in them.” The best correction is:

12. A heat engine absorbs from a hot reservoir and rejects to a cold reservoir. A student says its efficiency is . The correct efficiency is

13. A thermodynamic law can predict the relation between heat supplied, work done, and change in internal energy without knowing the path of every molecule. This is possible because thermodynamics

14. The derivation of for an ideal gas uses the fact that constant-pressure expansion work for a temperature change is

15. Assertion: When a hot cup is placed in a cooler room, heat transfer is from the cup to the room.
Reason: Heat transfer across a boundary occurs due to temperature difference and naturally proceeds from higher temperature to lower temperature in ordinary thermal contact.

16. A fixed ideal gas is compressed isothermally from to at temperature . The work done by the gas is

17. A gas is heated at constant volume and receives of heat. What is the change in internal energy?

18. Assertion: A real process involving heat flow through a finite temperature difference is irreversible.
Reason: The reverse transfer from colder body to hotter body would not occur by itself without some additional effect.

19. A copper block at is placed in contact with an iron block at . Before equilibrium is reached, the direction of net heat transfer is

20. A sample is doubled by adding an identical sample at the same pressure and temperature. Which set shows the variables that double?

21. A ideal gas is heated at constant pressure by . If , the heat supplied is . If , the increase in internal energy is

22. A gas is compressed, and of work is done on it. Under the convention that is work done by the gas, the value of is

23. A final comparison table is checked for process conditions and energy results.

The accurate judgement is

24. A real heat engine works between and . If it absorbs of heat per cycle, what is the maximum possible work output allowed by the Carnot limit?

25. A gas sample is described by its pressure , volume , temperature , and amount , without listing the position and velocity of each molecule. This is an example of a

26. For a fixed amount of ideal gas undergoing an isothermal process, the relation between pressure and volume is

27. A table lists quantities associated with a gas. Identify the row in which both entries are state variables.

28. A smooth - curve is normally drawn for a quasistatic process because

29. The notation differs from and because

30. From the same initial state, a fixed ideal gas expands to twice its initial volume by two reversible paths: one is isothermal at , and the other is adiabatic with . If , , and , the difference is closest to

31. The molar heat capacity at constant volume, , is defined by

32. Use the arrangement described below: a gas in a cylinder is compressed once by a rough piston and once by a frictionless piston, both very slowly. The two paths have the same initial and final volumes.
The rough-piston process is less reversible mainly because

33. Assertion: For a gas, is usually greater than .
Reason: For gases, because constant-pressure heating includes expansion work.

34. A sealed piston-cylinder contains of gas. During heating, of energy enters as heat and the gas does of work on the piston, but no gas escapes. How should this system be classified, and what kind of transfers occur?

35. A student compares two Carnot engines. Engine P works between and . Engine Q works between and . The correct comparison is

36. A statement claims: “A device that violates the Clausius statement can be used to make a device that violates the Kelvin-Planck statement.” This claim is best understood as

37. Use the arrangement described below: a gas in equilibrium is represented by a point on a - diagram. The same gas is then suddenly compressed so violently that pressure is not uniform inside it for a short time. During that short interval, a single point on the - diagram is unreliable because

38. A claim says, “If heat is supplied to a gas, its internal energy must increase.” The best correction is:

39. A sample of a substance requires of heat for a temperature rise of . Its molar heat capacity is

40. A full formula check gives the following entries.

The correct entry is

41. Use the graph description below.

The slope of this graph is

42. A gas at constant volume receives heat . A note says, “Since the gas has pressure, some of must become expansion work.” The best correction is:

43. A fixed amount of ideal gas goes from state P to state Q through two different paths. In both cases, the initial and final temperatures are and . What can be said about ?

44. A heat engine absorbs , rejects , and delivers work . A refrigerator removes heat from a cold chamber and needs work input . The row that gives dimensionless performance ratios is

45. A heat engine is claimed to absorb of heat from a single hot reservoir and convert all of it into of work in each cycle, with no other effect. This claim conflicts most directly with

46. A gas sample has , , and . Using , the number of moles is

47. Consider the following statements about free expansion of an ideal gas in an insulated rigid container.
I. The process is adiabatic because .
II. The work done against the surroundings is zero.
III. The process is reversible because .

48. A fixed ideal gas is taken around a cycle. During the cycle, it absorbs of heat in one part, rejects in another part, and rejects an additional during a third part. The net work done by the gas is

49. A gas does of work while its internal energy decreases by . The heat for the process is

50. In two processes connecting the same states of a gas, Path 1 has and Path 2 has . If for the change, the heat supplied along Path 1 and Path 2 is respectively