Question

The rate of diffusion of methane at a given temperature is twice that of a gas Z. What is the molecular weight of Z.?

Answer 1

Let rate of diffusion of gas z, r1 = a
Therefore, rate of diffusion of methane,r2 = 2 a
According to Graham's Law of Diffusion

r1/r2=√M2/M1

M1 = Molecular mass of gas z
M2 = Molecular mass of Methane = 16 g

Therefore,a/2a= √16/M2

Squaring both the sides,
1/4=16/M2
or, M2 = 16×4=64 g
Hence, the correct answer is 64 g