b
\(\mathrm{H}_2 \mathrm{SO}_4+2 \mathrm{NH}_3 \rightarrow\left(\mathrm{NH}_4\right)_2 \mathrm{SO}_4\)

Millimole of \(\mathrm{H}_2 \mathrm{SO}_4 \rightarrow 10 \times 2\)

So Millimole of \(\mathrm{NH}_3=20 \times 2=40\)

Organic \(\rightarrow\)  \(\mathrm{NH}_3\)

Compound  40 Millimole

\(\therefore\) Mole of \(\mathrm{N}=\frac{40}{1000}\)

wt. of \(\mathrm{N}=\frac{40}{1000} \times 14\)

\(\%\) composition of \(\mathrm{N}\) in organic compound

\(=\frac{40 \times 14}{1000 \times 1} \times 100\)

\(=56 \%\)