Question
Physics Question on Kinetic molecular theory of gases
The number of air molecules per cm3 increased from 3 × 1019 to 12 × 1019. The ratio of collision frequency of air molecules before and after the increase in the number respectively is :
A
0.25
B
0.75
C
1.25
D
0.50
Answer
0.25
Explanation
Solution
Collision frequency is given by 𝑍 = 𝑛𝜋𝑑 2𝑉𝑎𝑣𝑔, where n is number of molecules per unit volume.
𝑍1/ 𝑍2 = 𝑛1 /𝑛2 = 3/ 12 = 1/ 4 = 0.25