Class 11 Physics — Chapter 13: Kinetic Theory Online Test

1. The escape velocity from Earth is . At what temperature would rms velocity of hydrogen molecules equal escape velocity? M = 0.002 kg/mol.

2. Reynolds number is given by: Air () flows at velocity through a pipe of diameter . Calculate Reynolds number.

3. For a cylindrical pipe of length , inner radius , outer radius , and , temperature difference is . Calculate heat transfer per second.

4. If nitrogen gas has mean free path and average molecular speed , calculate diffusion coefficient.

5. If the enthalpy of vaporization of liquid helium at 4.2 K is , calculate the entropy change per mole during vaporization.

6. A 250 g block of ice at 0 °C is converted into water at 0 °C. Find the entropy change of the system. (, )

7. The macroscopic law is derived microscopically using:

8. Entropy () connects microscopic and macroscopic descriptions by the relation:

9. The Boltzmann constant () relates:

10. According to Arrhenius equation , how does temperature affect rate constant?

11. In chemical engineering, the diffusion coefficient for gases is often estimated using kinetic theory as:

12. Why is Brownian motion critical in nanomedicine for drug delivery systems?

13. According to Einstein’s 1905 explanation, the random motion of suspended particles in Brownian motion is caused by:

14. The mean free path is inversely proportional to:

15. A gas has . If 5 moles of this gas are heated at constant volume through 40 K, how much heat is absorbed?

16. The work done by an ideal gas in an isothermal process from to is:

17. According to the law of equipartition, the average energy per molecule of a monatomic ideal gas is:

18. For a monatomic ideal gas, the total average energy per molecule according to equipartition theorem is:

19. What happens to the pressure of a gas if the rms speed of its molecules doubles at constant volume?

20. Which formula relates pressure , number density , molecular mass , and mean square speed ?

1. In kinetic theory, what is the assumption about the size of gas molecules compared to the distance between them?

2. A superconductor undergoes a second-order phase transition at critical temperature . The specific heat shows:

3. Calculate mean free path of nitrogen at , . (Molecular diameter , ).

4. Who explained Brownian motion as evidence of molecular kinetic theory?

5. In the upper atmosphere, mean free path of molecules is very large because:

6. If 2 moles of water are vaporized at 100 °C and 1 atm, how much heat is absorbed? ()

7. Which property of a gas is directly proportional to the average kinetic energy of its molecules?

8. For a first-order phase transition, the Clausius–Clapeyron relation is:

9. Isotopes of an element have:

10. The ratio of specific heats () for a diatomic gas at moderate temperature is approximately:

11. Why is the factor included in the formula for mean free path?

12. A gas has a volume of 500 mL at 20°C. What will be its volume at 0°C at constant pressure?

13. At high temperatures, vibrational modes in molecules become active. How does this affect heat capacity?

14. Which of the following compounds has a purely covalent bond?

15. The pressure drop in laminar flow through a tube is given by: For oil of viscosity , flow rate , tube length , and radius , calculate .

16. In scuba diving, why is it dangerous to ascend quickly without exhaling?

17. Viscosity of a gas is related to mean free path by:

18. Which of the following graphs correctly represents Charles’s law?

19. Metallic bonds are best explained by which model?

20. A steel sphere of radius falls through oil of density . The sphere density is , terminal velocity . Find viscosity of oil.

21. According to kinetic theory, the volume of individual gas molecules compared to the total volume of the gas is:

22. For a gas with molecular diameter , at , and , calculate the mean free path.

23. Why does table salt () dissolve easily in water?

24. The melting point of a substance is defined as the temperature at which:

25. A composite wall has two layers in series: thickness of brick () and of plaster (). If area = and , calculate heat flow per second.

26. In statistical mechanics, the partition function is important because:

27. In enzyme catalysis, the “lock and key model” explains:

28. Which thermodynamic process involves heat transfer but no change in temperature?

29. In heterogeneous catalysis, why does increasing surface area of catalyst increase reaction rate?

30. Which of the following is a property of covalent compounds?

1. In the upper atmosphere, mean free path of molecules is very large because:

2. A glass capillary has length , radius . Under a pressure head of of water (), water () flows through it. Calculate volume flow rate.

3. Which of the following correctly represents root mean square (rms) speed?

4. A slab of glass of thickness has thermal conductivity . If the two surfaces are kept at and , calculate heat flow per unit area per second.

5. If the enthalpy of vaporization of liquid helium at 4.2 K is , calculate the entropy change per mole during vaporization.

6. Charles’s law states that for a fixed mass of gas at constant pressure:

7. Light can increase the rate of some chemical reactions (photochemical reactions) because:

8. The mean free path is inversely proportional to:

9. If 3 moles of a gas occupy 67.2 L at STP, then the volume of 1 mole of the gas is:

10. Why does the stratosphere contain a higher concentration of ozone compared to the troposphere?

11. A 100 nm gold nanoparticle in water has . What is its root mean square displacement in 1 second?

12. Which of the following compounds has a purely covalent bond?

13. If a copper rod of cross-sectional area , length , and conducts of heat, what is the temperature difference across its ends?

14. A composite wall has two layers in series: thickness of brick () and of plaster (). If area = and , calculate heat flow per second.

15. Calculate the molar heat capacity ratio () for a monatomic ideal gas.

16. If a nanoparticle of radius is suspended in water () at room temperature (), calculate its diffusion coefficient.

17. Which scientist discovered the relationship now known as Charles’s law?

18. The Chandrasekhar limit for white dwarfs is approximately:

19. For a diatomic gas (no vibrations), the adiabatic index is:

20. Which term in the Van der Waals equation accounts for molecular attractions?

21. Second-order (continuous) phase transitions are distinguished by:

22. The internal energy of an ideal monatomic gas is given by:

23. Why does ethanol () dissolve in water?

24. Who was the first scientist to propose that matter is made up of indivisible particles called “atoms”?

25. Viscosity of a gas is related to mean free path by:

26. The mean square displacement in one dimension according to Einstein is given by:

27. The mean free path for nitrogen at 300 K and 1 atm is . If viscosity , and is measured as , find approximate average molecular speed. Density .

28. At the critical point of a liquid–gas transition, the order parameter is:

29. The mean free path is inversely proportional to:

30. For 1 mole of diatomic gas (without vibrations), the molar heat capacity at constant pressure is:

31. For a linear triatomic molecule at high temperature, the expected using kinetic theory is:

32. The molar heat capacity at constant volume, , for a diatomic gas (ignoring vibrations) is:

33. Collision frequency between molecules is given by:

34. In probability distributions, the normalization condition requires:

35. Which of the following best describes dipole–dipole forces?

36. Which scientist is credited with formulating Avogadro’s law?

37. The molar specific heat at constant volume is defined as:

38. A balloon filled with air has a volume of 1.5 L at 27°C. What will be its volume at 127°C, if pressure remains constant?

39. For a linear triatomic molecule at high temperature where vibrational modes are active, the average energy per molecule becomes:

40. A wall of area , thickness , and conductivity separates rooms at and . Find heat loss per second.

41. The ratio of rates of effusion of hydrogen and oxygen is:

42. Why do smaller suspended particles show more vigorous Brownian motion compared to larger ones?

43. For a diatomic gas at room temperature, neglecting vibrations, the molar predicted by equipartition theorem is:

44. According to Arrhenius equation , how does temperature affect rate constant?

45. Which classical result emerges as the high-temperature limit of both Fermi–Dirac and Bose–Einstein statistics?

46. In a calorimeter experiment, 2 moles of a monatomic gas absorb 900 J of heat at constant volume. Find the rise in temperature.

47. What happens to the Maxwell–Boltzmann distribution curve when temperature increases?

48. A poor conductor of thickness and area allows of heat flow when the temperature difference across it is . Calculate its thermal conductivity.

49. What does the steric factor in collision theory account for?

50. If viscosity of a gas at 300 K is , predict viscosity at 600 K using Sutherland’s formula: Given .