Chemistry

Problem

E^\circ

for

\text{Cr}^{3+} + 3e^- \rightarrow \text{Cr}

and

\text{Cr}^{3+} + e^- \rightarrow \text{Cr}^{2+}

are

-0.74 \text{ V}

and

-0.40 \text{ V}

respectively.

E^\circ

for

\text{Cr}^{2+} + 2e^- \rightarrow \text{Cr}

is : a.

-0.91 \text{ V}

+0.91 \text{ V}

-1.14 \text{ V}

+0.34 \text{ V}