Which of the following equations would you use to find the final pressure of a gas after its temperature is changed, according to Gay Lussac's Law?

To find the final pressure of a gas after its temperature is changed, according to Gay Lussac's Law, the correct equation is derived from the relationship between pressure and temperature for a fixed amount of gas at constant volume. Gay Lussac’s Law states that the pressure of a gas is directly proportional to its absolute temperature when the volume is held constant.

The formulation P1/T1 = P2/T2 clearly illustrates this direct proportionality, where P1 and T1 are the initial pressure and temperature, and P2 and T2 are the final pressure and temperature. By rearranging this equation, you can find the final pressure of the gas after a temperature change, showcasing how an increase in temperature will lead to an increase in pressure if the volume remains constant.

Other provided options do not represent the appropriate relationship needed for this specific scenario. Choices regarding volume and other factors would not apply since Gay Lussac's Law focuses solely on the interaction between pressure and temperature. Thus, using P1/T1 = P2/T2 allows for straightforward calculations relating the two variables under the conditions established by Gay Lussac's Law.