c
\(\text { Let molarity of } {KMnO}_{4}={x}\)

\({KMnO}_{4}+{FeSO}_{4} \rightarrow {Fe}_{2}\left({SO}_{4}\right)_{3}+{Mn}^{2+}\)

\({n}=5 \quad {n}=1\)

(Equivalents of \({KMnO}_{4}\) reacted \()=\) (Equivalents of \({FeSO}_{4}\) reacted \()\)

\(\Rightarrow(5 \times x \times 10\, {ml})=1 \times 0.1 \times 10\, {ml}\)

\(\Rightarrow {x}=0.02\, {M}\)

Molar mass of \({KMnO}_{4}=158\, {gm} / {mol}\)

\(\Rightarrow \text { Strength }=({x} \times 158)=3.16\, {~g} / \ell\)