Question

Which of the following gases will have density of $1.8{\text{g L}}^{-1}$ at $760\text{torr}$ pressure and ${27}^{\circ }\text{C}$ ?
$(GivenR=0.082\text{L atm K}{}^{-1}{\text{mol}}^{-1},760\text{torr}=1\text{atm},0^{\circ }\text{C}=273\text{K})$

• A. $O_2$
• B. $C{O}_2$
• C. $N{H}_3$
• D. $S{O}_2$

Answer 1

The correct option is B $C{O}_2$

We know that
$PV=nRT\Rightarrow PV=\frac{m}{M}RT(\because n=\frac{m}{M})\Rightarrow PM=\frac{m}{V}RT\Rightarrow M=\frac{dRT}{P}(\because d=\frac{m}{V})\Rightarrow M=\frac{1.8\times 0.082\times 300}{1}\approx 44\text{g}$
$\therefore$ The gas will be $C{O}_2$.