Q. Two gases A and B having the same volume diffuse through a porous partition in 20 and 10 seconds respectively. The molecular mass of A is 49 u. Molecular mass of B will be
A) 25.00 u
B) 50.00 u
C) 12.25 u
D) 6.50 u
Explanation
[Solution from source] Time to diffuse equal volumes is proportional to √M (Graham's law). tA/tB = 20/10 = 2 = √(49/MB), so MB = 49/4 = 12.25 u. Taking the time ratio directly instead of its square gives 24.5 u. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.