Question

Given that,'
$E_{N{i}^{2+}/Ni}^{\circ }=-0.25V,E_{C{u}^{2+}/Cu}^{\circ }=+0.34V$
$E_{A{g}^{2+}/Ag}^{\circ }=+0.80V,E_{Z{n}^{2+}/Zn}^{\circ }=-0.76V$
Which of the following redox processes will not take place in specified direction?

• A. $N{i}^{2+}(aq.)+Cu\left(s\right)\to Ni\left(s\right)+C{u}^{2+}(aq.)$
• B. $Cu\left(s\right)+2A{g}^{+}(aq.)\to C{u}^{2+}(aq.)+2Ag\left(s\right)$
• C. $Cu\left(s\right)+2H^{+}(aq.)\to C{u}^{2+}(aq.)+H_2\left(g\right)$
• D. $Zn\left(s\right)+2H^{+}(aq.)\to Z{n}^{2+}(aq.)+H_2\left(g\right)$

Answer 1

The correct option is A $N{i}^{2+}(aq.)+Cu\left(s\right)\to Ni\left(s\right)+C{u}^{2+}(aq.)$

the species having higher reduction potential, will acts as cathode and reduction takes place;

in option A: $Cu$ is having higher reduction potential and in cell reaction oxidation of $Cu$ is taking place, which is not possible;

in rest of the options themetal having higher reduction potential is getting reduced.