Kinetic Theory Mock Test – Class 11 Physics

1. A gas has molecules, each of mass , in volume . If the pressure is , its rms speed is closest to

2. Study the table for a molecule colliding elastically with a wall perpendicular to the -axis. Select the row that gives the velocity components just after collision.

3. To change the expression into a formula involving , the key random-motion relation used is

4. Tiny pollen grains suspended in water are observed under a microscope. Their irregular zigzag motion is best explained by

5. A monatomic ideal gas is heated from to . At the same time, its volume doubles. The change in internal energy is, using ,

6. A claim says, “If the average velocity vector of a gas is zero, the pressure must also be zero.” The claim fails because pressure depends on

7. Study the table and select the row that best matches the usual molecular picture.

8. A molecule of mass hits a wall normally with speed and rebounds elastically. The magnitude of impulse delivered to the wall is

9. Hydrogen gas has molar mass , while oxygen gas has molar mass . At the same temperature, the ratio is

10. Match the symbols with their usual meanings in kinetic theory.

11. Use the arrangement described below.

If is made larger while number density is unchanged, the mean free path generally

12. The unit of mean free path is

13. A gas has molar mass . If , then molecules of this gas have total mass

14. Consider the following statements about molecular speed distribution.
I. At a fixed temperature, all molecules of a gas have exactly the same speed.
II. Raising temperature shifts the distribution toward higher speeds.
III. For a fixed number of molecules, the area under the speed-distribution curve remains fixed.

15. A monatomic ideal gas has at . It is cooled at constant volume until its pressure becomes of the original pressure. Using , the decrease in internal energy is closest to

16. A gas molecule has translational and rotational active degrees of freedom. The average energy of of this gas at , using , is closest to

17. Match the following kinetic-theory relations with the condition or meaning they most directly represent.

18. A gas has molecular diameter . If is doubled at the same number density, the mean free path becomes

19. Study the table for a fixed amount of monatomic ideal gas. Select the row that gives the correct sign of .

20. In a gas at ordinary conditions, the average intermolecular separation is generally

21. Use the arrangement described below.

During the free part of its motion between collisions, the molecule is assumed to move

22. A gas has pressure , molar mass , and absolute temperature . From the ideal-gas equation, its density is

23. A gas sample has , , and . Using , the temperature and rms speed are closest to

24. A gas sample contains molecules in . Each molecule has mass , and . The pressure is closest to

25. A fixed mass of gas at constant pressure occupies at . Its volume at is

26. For an ideal gas, the number density can be written as . Substituting this in shows that, for fixed and , mean free path is

27. An ideal gas has . If its heat capacities are explained by active degrees of freedom with vibrations neglected, the most suitable interpretation is

28. A fixed amount of ideal gas changes from , , to , . What is ?

29. Assertion: In the kinetic theory of an ideal gas, molecular collisions with the container wall are assumed to be elastic.
Reason: If wall collisions were not elastic, the gas molecules would continuously lose kinetic energy to the wall in the simple model.

30. A sample is described by the number of molecules , not by the number of moles . The ideal-gas equation should then be written as

31. Study the table and identify the rows with correct expected behaviours for ideal-gas and real-gas limits.

32. A gas sample changes from state to state , with the amount of gas fixed. The data are , , , , and . The final volume is

33. A gas occupies at pressure and temperature . Using , the amount of gas is closest to

34. Which row contains a fully suitable SI unit pairing for the listed gas quantities?

35. A graph is plotted with pressure on the vertical axis and on the horizontal axis for a gas of fixed density . The slope of the straight line is

36. A gas has molar mass and amount . Its total mass is

37. A diatomic ideal gas at ordinary temperature has at . If , its internal energy and are closest to

38. One mole of a monatomic ideal gas has translational kinetic energy

39. Two ideal gases P and Q have the same density and the same pressure. Gas P has molar mass , while gas Q has molar mass . Their absolute temperatures satisfy

40. A gas of molar mass has rms speed . Taking , its absolute temperature is closest to

41. Read the situation below and answer the question.

This molecular picture is most directly related to

42. The table gives four statements about mole and molecule count. Select the row that needs correction.

43. The speed distribution curve of a gas is drawn with speed on the horizontal axis and number of molecules on the vertical axis. When the temperature is increased, the curve generally

44. Study the table and identify the row that best represents molecular size and separation in a gas.

45. A diatomic ideal gas at ordinary temperature has . Its value of is

46. A molecule of mass moves inside a cubical vessel of side . Its velocity component perpendicular to one wall is . For elastic collisions with that wall, the average force on the wall due to this molecule is

47. A fixed amount of gas is sealed in a rigid container. Its pressure is at . What is its pressure at ?

48. A graph is drawn with average translational kinetic energy per molecule on the vertical axis and absolute temperature on the horizontal axis. The graph is expected to be

49. The molecular picture is most useful because it connects macroscopic observations with microscopic causes. In this context, pressure of a gas is a macroscopic quantity because it describes

50. Match the quantities with their meanings.