Question

Cu (s) + Ni+2 (aq) → Cu+2 (aq) + Ni (s)

Answer 1

This is a redox reaction

During the reaction, the oxidation number of Copper increases from 0 to +2

Increase in the oxidation number is oxidation. Hence Cu is oxidized

$Cu_{(s)}\to\>$ Cu$^{2+}$ $+2e^-$

Cu is the reducing agent

Oxidation number of Nickel decreases from +2 to 0.

Hence Ni is reduced

$Ni^{2+}_{(aq)}+2e^-\to$ Ni$_{(s)}$

$\therefore\>Ni^{2+}$ is the oxidizing agent.