Answer: temperature and number of particles are constant
Step-by-step explanation:
In 1662, Robert Boyle put forth a theory that the volume of a gas will be inversely proportional to the pressure it exerts so long as the temperature is constant and the number of particles or mass is constant as well.
This means that at a constant temperature, the higher the volume of a gas, the less pressure it exerts which makes sense because more volume means that the gas particles are more dispersed which means that they would only be able to apply minimal pressure wherever they are because the particles are not numerous enough to have much effect.