How would the graph change if a catalyst were used
a) a would increase
b) c would decrease
c) d would decrease
d) e would decrease

Option B.

C (activation energy) would decrease meaning that the catalyst provides an alternative path where lower activation energy is needed for a reaction to  take place.

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Force of the collisions increases due to increase in temperature.

Explanation:

Increase in temperature affects the average speed and kinetic energy of the particles.

The average speed of the gas particles gets increased , Kinetic energy of the gas particles also gets increased.

If the volume is held constant, the increased speed of the gas molecules results in more frequent and more forceful collisions with the walls of the container, therefore increasing the pressure.

Therefore, force of the collisions increases due to increase in temperature.