Question

The density of a gas is $2$, relative to nitrogen under the same condition . The molecular weight of the gas is:

• A. $5.6$
• B. $28$
• C. $56$
• D. $14$

Answer 1

The correct option is D $14$

Using the relation,

$\rho =\frac{PM}{RT}$

Under the same conditions,

$\rho \propto M$

$\Rightarrow \frac{M_1}{M_2}=\frac{{\rho }_1}{{\rho }_2}$

$\Rightarrow M_2=M_1\frac{{\rho }_2}{{\rho }_1}$

Given, ${\rho }_2=2{\rho }_1$, and Molecular weight of Nitrogen=$M_1=28gmo{l}^{-1}$

$\Rightarrow M_2=28\times \frac{2{\rho }_1}{{\rho }_1}$

$\Rightarrow M_2=56gmo{l}^{-1}$