When the temperature of a gas decreases at constant volume, its a. pressure increases. b. mass increases. c. pressure decreases. d. particles move faster.

a. pressure increases

b. particles move faster

Explanation:

When the temperature of a gas at constant volume increases, it means the kinetic energy of the gas particles will also increase and this means that the particles will move at a faster speed.

Also, since the particles are moving faster, it means they will be hitting the walls of the container carrying the gas at a faster rate.

And the higher the force, the higher the Pressure.