Question

Two separate bulbs contain gas A and gas B. The density of gas A is twice as that of B. The molecular mass of A is half as that of B. If temperature is constant, the ratio of the pressure of A and B is

• A. $1:1$
• B. $1:2$
• C. $4:1$
• D. $2:1$

Answer 1

The correct option is C $4:1$

$d=\frac{PM}{RT}$
Given:
$\frac{d_A}{d_B}=2$ and $\frac{M_A}{M_B}=\frac{1}{2}$
$\frac{d_A}{d_B}=\frac{P_A{M}_A}{RT}\times \frac{RT}{P_B{M}_B}$
Putting the values:
$\frac{P_A}{P_B}=4:1$