Question

The density of gas A is twice that of B at the same temperature the molecular weight of gas B is thrice that of A. The ratio of pressure of gas A and gas B will be :

• A. 1 : 6
• B. 7 : 8
• C. 6 : 1
• D. 1 : 4

Answer 1

The correct option is C 6 : 1

The ideal gas equation is $PV=nRT=\frac{w}{M}RT$

$P=\frac{\rho }{M}RT$.

At constant pressure, $P\propto \frac{\rho }{M}$

Hence, $\frac{P_A}{P_B}=\frac{{\rho }_A{M}_B}{{\rho }_B{M}_A}=\frac{2\times 3}{1\times 1}=6:1$

Hence, the correct option is $\text{C}$