Which of the following best describes how each gas in a mixture exerts pressure?

The statement that each gas exerts pressure according to its mole fraction in the mixture is rooted in Dalton's Law of Partial Pressures. According to this law, in a mixture of non-reacting gases, the total pressure exerted by the mixture is equal to the sum of the partial pressures of each individual gas. The partial pressure of a gas is proportional to its mole fraction, which represents the ratio of the number of moles of that gas to the total number of moles of all gases in the mixture.

When considering a mixture, each gas contributes to the overall pressure in proportion to how much of that gas is present relative to the total amount of gas. This means that a gas with a higher mole fraction will exert a greater partial pressure than one with a lower mole fraction. As such, the correct description of how each gas in a mixture exerts pressure considers the inherent relationship between the concentration of that gas and the total pressure of the mixture.

Thus, understanding how mole fraction correlates with partial pressure helps clarify the behavior of gases in mixtures, demonstrating that the pressure exerted by each gas is indeed dependent on its relative amount in the system.