How can you increase gas pressure in a container?
Pressure of the gas in a container is created by the number of collisions the molecules undergo with each other and with the surface of the container. Increasing the the number of collisions will increase the pressure.
There are several ways to increase the number of collisions.
You could add more molecules. More molecules in the same size container would increase the number of times molecules would collide.
You could increase the temperature. Increasing the temperature would increase the speed at which the molecules would move and therefore increase the number of collisions that would take place in the container.
You could decrease the size of the container, this would force the molecules into a smaller area and therefore increase the number of collisions that take place.
I hope this was helpful.