Question

the pressure exerted a given mass of a gas in a container is what?

Answer 1

Here your Answer

Dalton's Law of Partial Pressure:

At constant temperature, the pressure exerted by a mixture of two or more non-reacting gases in enclosed in a definite volume, is equal to the sum of the individual pressure which each gas exerts, if present alone in the same volume.

hope it helps you....!!!

Answer 2

Because in the gaseous state, the particles move about randomly at high speed. Due to this random movement, the particles hit each other and also the walls of the container. The pressure exerted by the gas is because of this force exerted by gas particles per unit area on the walls of the container.