If \( 3.01 \times 10^{20} \) molecules are removed from \( 98 \mathrm{mg} \) of \( \mathrm{H}_{2} \mathrm{SO}_{4} \), then number of moles of
\( \mathrm{H}_{2} \mathrm{SO}_{4} \) left are

1 mole of \(\mathrm{H}_{2} \mathrm{SO}_{4}=6.022 \times 10^{23}\) molecules of \(\mathrm{H}_{2} \mathrm{SO}_{4}=98 \mathrm{~g}\) of \(\mathrm{H}_{2} \mathrm{SO}_{4}\)
\(98 \mathrm{mg}=1 \times 10^{-3}\) moles \(=6.022 \times 10^{20}\)
molecules of \(\mathrm{H}_{2} \mathrm{SO}_{4}\)
No. of molecules removed \(=3.01 \times 10^{20}\)
No. of molecules left \(=6.023 \times 10^{20}-3.01 \times 10^{20}\)
\(=6.023 \times 10^{20}-3.01 \times 10^{20}\)
\(=3.01 \times 10^{20}\) molecules left
\(6.022 \times 10^{23}\) molecules of \(\mathrm{H}_{2} \mathrm{SO}_{4}=1\) mole
1 molecule \(=\frac{1}{6.022 \times 10^{23}}\) moles
\(3.01 \times 10^{20}\) molecules \(=\frac{3.01 \times 10^{20}}{6.023 \times 10^{20}}\)
\(=0.5 \times 10^{-3}\) mol