(N/A) To construct a galvanic cell,we identify the anode and cathode based on standard reduction potentials.
$E^o_{Mg^{2+}|Mg} = -2.37 \ V$ (Anode,as it is more negative)
$E^o_{Co^{2+}|Co} = -0.28 \ V$ (Cathode,as it is more positive)
In a galvanic cell,oxidation occurs at the anode and reduction occurs at the cathode.
Anode reaction: $Mg(s) \rightarrow Mg^{2+}(aq) + 2e^-$
Cathode reaction: $Co^{2+}(aq) + 2e^- \rightarrow Co(s)$
The symbolic representation of a galvanic cell is written as: $\text{Anode} | \text{Anode electrolyte} || \text{Cathode electrolyte} | \text{Cathode}$
Therefore,the representation is: $Mg(s) | Mg^{2+}(aq) || Co^{2+}(aq) | Co(s)$