Question 1

Which postulate of the Kinetic Molecular Theory explains why gases are compressible?

Accepted Answer

The volume of individual gas molecules is negligible compared to the total volume of the gas.

Question 2

According to the Kinetic Molecular Theory, what happens to the average kinetic energy of gas particles when the temperature is doubled?

Accepted Answer

It doubles.

Question 3

A balloon filled with helium gas shrinks when placed in a cold environment. Which explanation best fits this observation using the Kinetic Molecular Theory?

Accepted Answer

The gas particles move slower, resulting in fewer and less forceful collisions with the balloon walls.

Question 4

Which equation correctly relates the average kinetic energy of a gas particle to temperature?

Accepted Answer

$$KE = \frac{3}{2}k_B T$$

Question 5

Graham's Law of Effusion can be derived from which property of gas particles?

Accepted Answer

Their kinetic energy

Question 6

If two gases, A and B, are at the same temperature, which statement is true about their average kinetic energies?

Accepted Answer

Both gases have the same average kinetic energy.

Question 7

Which formula represents Graham's Law of Effusion for two gases, A and B?

Accepted Answer

$$\frac{rate_A}{rate_B} = \sqrt{\frac{M_B}{M_A}}$$

Question 8

A sample of $$O_2$$ and $$H_2$$ are at the same temperature. Which gas will have a higher average velocity and why?

Accepted Answer

$$H_2$$, because it has a lower molar mass.

Question 9

If the temperature of a gas is increased from 300 K to 600 K, what happens to the root mean square speed ($$v_{rms}) of $$the gas particles?

Accepted Answer

It increases by a factor of $$\sqrt{2}.$$

Question 10

Which of the following best explains why lighter gases effuse faster than heavier gases?

Accepted Answer

Lighter gases have higher average velocities at the same temperature.

Question 11

A medical device uses effusion to separate $$N_2$$ and $$CO_2. If $$the molar mass of $$N_2 is 28 g/$$mol and $$CO_2 is 44 g/$$mol, what is the ratio of their rates of effusion ($$rate_{N_2$}/rate_{CO_2$}$$)?

Accepted Answer

$$\sqrt{\frac{44}{28}}$$

Question 12

Which scenario would result in a decrease in the pressure of a gas inside a sealed container, according to the Kinetic Molecular Theory?

Accepted Answer

Decreasing the temperature

Question 13

Which of the following is NOT an assumption of the Kinetic Molecular Theory for ideal gases?

Accepted Answer

Gas particles exert attractive forces on each other.

Question 14

A tank contains equal moles of $$He$$, $$N_2$$, and $$CO_2 at $$the same temperature. Which gas has the greatest number of particles colliding with the walls per second?

Accepted Answer

$$He$$

Question 15

Which graph best represents the distribution of molecular speeds for $$O_2 at 100 K $$compared to 300 K?

Accepted Answer

The 100 K curve is narrower and peaks at a lower speed than the 300 K curve.

Question 16

A gas sample is cooled at constant volume. What happens to the pressure and why?

Accepted Answer

Pressure decreases because particles move slower and collide less forcefully.

Question 17

Which of the following real-world scenarios is best explained by Graham's Law of Effusion?

Accepted Answer

The rapid escape of hydrogen gas from a punctured balloon compared to oxygen.

Question 18

If the molar mass of gas A is four times that of gas B, what is the ratio of their rates of effusion ($$rate_A/rate_B$$)?

Accepted Answer

$$\frac{1}{2}$$

Question 19

Which statement is true about the velocity distribution of gas particles at higher temperatures?

Accepted Answer

The distribution becomes wider and peaks at higher velocities.

Question 20

A hospital uses a device to separate $$O_2$$ and $$He by $$effusion. If both gases are at the same temperature, which will effuse faster and why?

Accepted Answer

$$He$$, because it has a lower molar mass.

Kinetic Molecular Theory and Gas Behavior: Ideal Gases, Graham’s Law, and Velocity Distributions

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