Experimental values, At \(STP.\)

\(V_{1}=40 \,\mathrm{mL}\)

\(V_{2}=?\)

\(T_{1}=300 \,\mathrm{K}\)

\(T_{2}=273 \,\mathrm{K}\)

\(P_{1}^{2}=725-25=700\, \mathrm{mm}\)

\(P_{2}=760\, \mathrm{mm}\)

\(\frac{P_{1} V_{1}}{T_{1}}=\frac{P_{2} V_{2}}{T_{2}}\)

\(V_{2}=\frac{P_{1} V_{1} T_{2}}{T_{1} P_{2}}=\frac{700 \times 40 \times 273}{300 \times 760}=33.52\, \mathrm{mL}\)

\(22400\, \mathrm{mL}\) of \(\mathrm{N}_{2}\) at \(STP\) weighs \(=28\, \mathrm{g}\)

\(\therefore 33.52\, \mathrm{mL}\) of \(\mathrm{N}_{2}\) at \(STP\) weighs \(=\frac{28 \times 33.52}{22400}\)

\(=0.0419\; \mathrm{g}\)

\(\%\) of \(\mathrm{N}=\frac{\text { Mass of nitrogen at STP }}{\text { Mass of organic compound taken }} \times 100\)

\(=\frac{0.0419}{0.25} \times 100=16.76 \%\)