"Does a solid?""Nope". "Does a liquid?""Not totally."
Explanation:
"But does a gas?"
Yes indeed they does. And "Dalton's Law of Partial Pressures" states that in a gaseous mixture, the pressure exerted by a component gas, is the same pressure it would exert if it ALONE occupied the container. Partial pressures of component gases thus add together to give the total pressure.