$Cr_{(s)} | Cr^{3+}_{(0.1\,M)} | | Fe^{2+}_{(0.01\,M)} | Fe;$
$E^0_{{cr}^{3+} |Cr} = -0.72 \,V,$ $ E^{0}_{{Fe}^{2+}{| Fe}}$ $= -0.42 \,V$
\(\, = \,\,\,0.30 - \frac{{0.0592}}{6}\,\,\,\log \,\,\,\frac{{{{[0.1]}^2}}}{{{{[0.01]}^3}}}\)
\( = \,\,0.30 - 0.009867\,\,\log \,\,\frac{{1 \times {{10}^{ - 2}}}}{{1 \times {{10}^{ - 6}}}}\)
\(= 0.30 - 0.00987\, log\, 1 × 10^{4} \) \(= 0.30 - (0.00987 × 4)\) \(= 0.30 - 0.03948 \) \(= 0.26\, V\)