Question

Under identical conditions of temperature the density of a gas $X$ is three times that of gas $Y$ while molecular mass of gas $Y$ is twice that of $X$. The ratio of pressures of $X$ and $Y$ will be

• A. $6$
• B. $1/6$
• C. $2/3$
• D. $3/2$

Answer 1

The correct option is A $6$

According to the ideal gas equation

$PV=nRT$

Ratio of pressure,

$\frac{P_1}{P_2}=\frac{\left(M_1/V_1\right)RT}{M_1}\times \frac{1}{\frac{\left(M_2/V_2\right)RT}{M_2}}$

$=\frac{\left(d_1\right)RT}{M_1}\times$ $\frac{1}{\frac{\left(d_2\right)RT}{M_2}}$

$=\frac{\left(2d_2\right)RT}{M_1}\times$ $\frac{1}{\frac{\left(d_2\right)RT}{3M_1}}=6$

Option A is correct.