The number of air molecules per cm 3 is increased from 3 × 10 19 to 12 × 10 19 . The ratio of collision frequency of air molecules before and after the increase in number respectively is :

Step-by-step solution

The given data is n 1 = 3 × 10 19 n 2 = 12 × 10 19 The mean time between two collision has the meaning of a period τ , since it indicates the repetitive time intervals in which on average collisions take place. The reciprocal of the time τ can be understood as the collision frequency   f , which indicates the number of collisions per unit time.The collision frequency is also directly proportional to the number molecules per unit volume. f ∝ 1 τ ⇒ f ∝ n ⇒ f 1&#16