Given below are two statements. One is labelled as Assertion (A) and the other is labelled as reason (R).
(A): At constant volume on increasing temperature the collision frequency increases.
 (R): Collision frequency is directly proportional to temperature of the gas
In the light of the given statements, choose the correct answer from the options given.

So, an increase in temperature results in an increase of pressure and hence the increase in number of collisions. Therefore, we found that, at constant volume when the temperature is increased the number of collisions per unit time will increase. Hence assertion is true.

 The collision frequency is directly proportional to the square root of the absolute temperature. Hence reason is wrong.

so, A is true R is false.