If the gas particles suddenly stopped moving, the pressure of the gas would drop to zero.
Pressure is caused by the collisions of gas particles with the walls of a container. When gas particles are moving, they collide with the walls of the container and exert a force on them, creating pressure. If the gas particles suddenly stopped moving, they would no longer collide with the walls of the container and the pressure would drop to zero.
However, it is important to note that in reality, it is impossible for gas particles to suddenly stop moving. This is because gas particles are always in motion due to their kinetic energy. If the gas particles were to stop moving, they would need to lose all of their kinetic energy, which is not possible according to the laws of thermodynamics.