Which of the following will increase the pressure of a gas?

Increasing the number of gas particles directly influences the pressure of a gas as described by the Ideal Gas Law, which states that pressure is proportional to the number of particles, assuming volume and temperature remain constant. When more gas particles are added to a container, these particles collide with the walls of the container more frequently, leading to an increase in pressure. This effect can be understood through the kinetic molecular theory of gases, which explains that pressure results from collision events between gas molecules and the walls of their container.

In this scenario, while increasing the volume would generally decrease pressure (since the same number of molecules occupy a larger space), decreasing the number of gas particles would obviously reduce the frequency of collisions, thus lowering the overall pressure. Similarly, lowering the temperature would reduce the kinetic energy of the particles, leading to fewer collisions and a decrease in pressure. Therefore, increasing the number of gas particles is the correct approach to raise gas pressure in a fixed volume.