Question

Why does the pressure exerted by a gas at a constant temperature decrease when the volume of the gas is increased?

Answer 1

Because for a given quantity of gas at constant temperature, `P_1V_1=P_2V_2`

Explanation:

And thus, `P_2=P_1V_1/V_2`

Since by definition of the problem `V_1/V_2<1`, because `V_2` has INCREASED with respect to `V_1`, `P_2`, is less than `P_1`, the initial pressure.