For the galvanic cell reaction, expressed below using shorthand notation, what half-reaction occurs at the cathode?

Zn (s) Zn2 + (aq) Ni2 + (aq) Ni (s)

A) Zn (s) → Zn2 + (aq) + 2 e

B) Zn2 + (aq) + 2 e - → Zn (s)

C) Ni (s) → Ni2 + (aq) + 2 e

D) Ni2 + (aq) + 2 e - → Ni (s)

D

Explanation:

In considering the half cell reactions in electrochemical cells, we consider the standard electrode potential of the two half cells. The more negative electrode potential will be the anode and the less negative electrode potential will be the cathode. The electrode potentials of Ni2 + (aq) / Ni (s) is - 0.25V while that of Zn2 + (aq) / Zn (s) is - 0.76.

Hence the selected option is the cathodic half reaction equation