Question

The pressure exerted by a gas on its container is directly proportional to ________.

Answer 1

The pressure exerted by a gas on its container is directly proportional to the absolute temperature of the gas.

This result is known as "Gay-Lussac law", which states that for an ideal gas with fixed volume (like the gas in the container), the ratio between pressure and absolute temperature of the gas is constant:
$\frac{p}{T}=k$
where p is the pressure of the gas and T its absolute temperature.