Question

The vapour densities of two gases are in the ratio of 1 : 3. Their molecular masses are in the ratio of:

• A. 1 : 3
• B. 1 : 2
• C. 2 : 3
• D. 3 : 1

Answer 1

Answer: (A)

1 : 3

Given:

$\frac{(VapourDensity{)}_1}{(VapourDensity{)}_2}=\frac{1}{3}$

We know,

Molecular Mass$=2\times VapourDensity$

$\frac{\frac{(Molmass{)}_1}{2}}{\frac{(Molmass{)}_2}{2}}=\frac{1}{3}$

$\frac{(Molecularmass{)}_1}{(Molecularmass{)}_2}=\frac{1}{3}$ or $1:3$