$Cr_{(s)} | Cr^{3+}_{(0.1\,M)} | | Fe^{2+}_{(0.01\,M)} | Fe;$
$E^0_{{cr}^{3+} |Cr} = -0.72 \,V,$ $ E^{0}_{{Fe}^{2+}{| Fe}}$ $= -0.42 \,V$
$= + 0.34 \,volt, I_2/ 2I- = + 0.53\, volt$
$Z{n^{2 + }}\,(aq)\, + \,2e\, \rightleftharpoons \,Zn\,(s)\,;\, - \,0.762\,V$
$C{r^{3 + }}\,(aq)\, + \,3e\, \rightleftharpoons \,Cr(s)\,;\, - \,0.740\,\,V$
$2{H^ + }\,(aq)\, + \,2e\, \rightleftharpoons \,{H_2}(g)\,;\,\,\,0.00\,\,\,V$
$F{e^{3 + }}\,(aq)\, + \,e\, \rightleftharpoons \,F{e^{2 + }}(aq)\,;\,\,\,0.770\,\,\,V$
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