PSAT Math Multiple-Choice Question 715: Answer and Explanation

Question: 715

The ideal gas equation is PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature. According to the equation, the volume of a gas is inversely related to

• A. the number of moles.
• B. gas constant.
• C. temperature.
• D. none of the above.

Correct Answer: D

Explanation:

(D) Solve for V:

Recall that, in general, y is directly proportional to x if y = cx for some constant c, and y is inversely proportional if . In our case, we are told that R is the gas constant, so we can think of this as our constant. So V is directly proportional to n> and T. If you increased either of these variables, V would also increase. V is inversely proportional only to P, which isn't an answer choice. So choice (D) is the correct answer.