a
Moles of \(e ^{\ominus}=\left(\frac{8 \times 60 \times 2}{96000}\right)\)

Using stoichiometry; theoritically

\(\frac{ n _{ e ^{\ominus}} used }{6}=\)\(\frac{ n _{ cr ^{+3}} \text {produced }}{2}\)

\(\Rightarrow n _{ cr ^{+3}}\) produced \(=\frac{2}{6} \times \frac{8 \times 60 \times 2}{96000}\)

\(=\frac{0.02}{6}\)

\(\Rightarrow wt _{ cr ^{+3}}\) theoritically produced

\(=\left(\frac{0.02}{6} \times 52\right) g\)

\(\Rightarrow \%\) efficiency \(=\frac{0.104 g }{\left(\frac{0.02 \times 52}{6}\right) g } \times 100\)

\(=60 \%\)