Consider two boxes containing ideal gases A and B such that their temperatures, pressures and number densities are same. The molecular size of A is half of that of B and mass of molecule A is four times that of B. If the collision frequency in gas B is 32 1018 /s then collision frequency in gas A is /s.
- 8 1018
- 2 1018
- 32 1018
- 4 1018
Answer
(4) 4 1018
Solution
Collision frequency = v , where mean free path = 1 2 d2 n
= 2 d2 n v
v = 8kT m 1 m (same T)
d2 m (same n)
A B = ( dAdB )2 mBmA = ( 12 )2 14 = 18
A = 32 10188 = 4 1018 s-1
Answer: (4)