Unit 3: Gases

51. The rate of diffusion of a gas is:

a) Directly proportional to its molar mass
b) Directly proportional to the square root of its temperature
c) Inversely proportional to the square root of its molar mass
d) Inversely proportional to its volume
Answer: c) Inversely proportional to the square root of its molar mass

52. In which of the following scenarios would the volume of a gas be least affected?

a) Increasing the temperature while keeping pressure constant
b) Decreasing the pressure while keeping temperature constant
c) Increasing the number of moles while keeping pressure constant
d) Decreasing the volume while keeping temperature constant
Answer: d) Decreasing the volume while keeping temperature constant

53. If two gases are combined in a container, the total pressure of the mixture is the sum of:

a) The partial pressures of the individual gases
b) The absolute pressures of the individual gases
c) The partial volumes of the individual gases
d) The total volumes of the individual gases
Answer: a) The partial pressures of the individual gases

54. The effusion rate of a gas is proportional to:

a) Its molar mass
b) Its temperature
c) Its density
d) Its pressure
Answer: b) Its temperature

55. The concept of “ideal gas” is most closely approximated by:

a) Gases at high temperatures and low pressures
b) Gases at low temperatures and high pressures
c) Gases at low temperatures and low pressures
d) Gases at high temperatures and high pressures
Answer: a) Gases at high temperatures and low pressures

56. The volume of a gas decreases as:

a) Temperature decreases and pressure increases
b) Temperature increases and pressure decreases
c) Temperature decreases and pressure decreases
d) Temperature increases and pressure increases
Answer: a) Temperature decreases and pressure increases

57. The partial pressure of a gas in a mixture can be found using:

a) The volume of the gas
b) The density of the gas
c) The fraction of the gas in the mixture
d) The temperature of the gas
Answer: c) The fraction of the gas in the mixture

58. If the temperature of a gas is doubled while keeping pressure constant, what happens to the volume?

a) It remains the same
b) It is halved
c) It doubles
d) It triples
Answer: c) It doubles

59. The concept that gas molecules are in constant motion and collide with each other and the walls of their container is part of which theory?

a) Kinetic molecular theory
b) Dalton’s theory
c) Van der Waals theory
d) Avogadro’s theory
Answer: a) Kinetic molecular theory

60. In a gas mixture, the partial pressure of a gas is the:

a) Total pressure of the gas
b) Pressure of the gas if it were alone in the container
c) Average pressure of the gas
d) Difference between the total pressure and the pressure of other gases
Answer: b) Pressure of the gas if it were alone in the container