Here it is
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QuoteThe rate of diffusion two gases A and B are in the ratio 1 : 4. If the ratio of their masses present In the mixture is 2 :3. The ratio of their mole fraction is : (9 ^1/3 = 2.08)

μA/μB=√(MB/MA)=1/4
Taking square of both sides
MA = 16MB

Mole of A = 2x/MA= 2x/16MB
Moles of B = 3x/MB
Total moles = 2x/16MB  + 3x/MB

= 50x /16MB

X_A=2x/16MB     ∗ 16MB/50X=0.04

X_A+ X_B=1
Calculate X_B and take their ratio