Answer
See the answer below.
Work Step by Step
In a voltaic cell, anode is the electrode where the oxidation takes place and cathode is the electrode where the reduction occurs. So, the oxidation half-reaction
$Ni(s)\rightarrow Ni^{2+}+2e^{-}$ takes place at the anode and the electrode at which the reduction half-reaction $2Ag^{+}(aq)+2e^{-}\rightarrow 2Ag(s)$ occurs is cathode.
