Correct option is (a)
EoCu2+/Cu = +0.34 V
EoZn+2/Zn = -0.76 V
Zn + Cu+2 → Zn+2 + Cu
Eo = 0.34 - (-0.76)
Eo = 1.1 V
Using nernst equation
Ecell = 1.1 V - \(\frac{0.0591}2log\frac{Zn^{+2}}{Cu^{+2}}\)
Ecell = 1.1 V - \(\frac{0.0591}2logK_{eq}=0\)
1.1 = \(\frac{0.0591}2log\frac{[Zn^{+2}]}{[Cu^{+2}]}\)
(a) If Eext > 1.1V, means reaction gas backward direction . Cu dissolve at copper electrode and Zn deposits at Zn electrode.
(b) If Eext > 1.1V, Cu oxidize and Zn reduced it means, electron flows rom Cu to Zn.
(c) If Eext > 1.1V, it means there is no oxidation or reduction take place therefore no flow of current occur.
(d) If Eext > 1.1V, it means oxidization of Zn and reduction of Cu take place. Zn dissolves at anode and Cu deposits at cathode.