2 moles of \(\mathrm{N}_{2} \mathrm{O}_{4}(\mathrm{~g})\) is kept in a closed container at \(298 \mathrm{~K}\) and under 1 atm pressure. It is heated to \(596 \mathrm{~K}\) when \(20 \%\) by mass of \(\mathrm{N}_{2} \mathrm{O}_{4}(\mathrm{~g})\) decomposes to \(\mathrm{NO}_{2}\). The resulting pressure is

\[
\begin{array}{cc}
\mathrm{N}_{2} \mathrm{O}_{4} & 2 \mathrm{NO}_{2} \\
1 \mathrm{~mol} & 92 \mathrm{~g} \\
2 \mathrm{~mol} & 2 \times 92 \mathrm{~g} \quad \text { Initially } \\
2 \times 92-2 \times 92 \times 0.2 & 2 \times 2 \times 92 \times 0.2 \text { At cqulibrium } \\
=147.2 & =73.6 \mathrm{~g} \\
=1.6 \mathrm{~mol} & =0.8 \mathrm{~mol}
\end{array}
\]
Total moles \(=1.6+0.8=2.4\)
At constant volume,
\[
\begin{aligned}
\frac{\mathrm{P}_{1}}{\mathrm{n}_{1} \mathrm{~T}_{1}} &=\frac{\mathrm{P}_{2}}{\mathrm{n}_{2} \mathrm{~T}_{2}} \\
\frac{1}{2 \times 298} &=\frac{\mathrm{P}_{2}}{2.4 \times 596} \\
\mathrm{P}_{2} &=\frac{2.4 \times 596}{596} \\
&=2.4 \mathrm{~atm}
\end{aligned}
\]