What takes place when zinc metal is added to an aqueous solution containing magnesium nitrate and silver nitrate?

(P) Zn is oxidized.

(Q) Mg²⁺ is reduced.

(R) Ag⁺ is reduced.

(S) No reaction takes place

The relatively positive electrode potential values indicate that no forward reaction—a reduction event involving the addition of electrons—can occur.

Electrodes with relatively low electrode potential values, however, imply that the possibility of a reverse reaction—an oxidation reaction involving the loss of electrons—is real.
Zinc's electrochemical potential is 0.76 Mg²⁺, 2.37 Ag⁺, and 0.79 Zn.
Magnesium Nitrate and Zinc do not react when they are combined. Magnesium is more reactive than zinc, and as a result, it tends to create positive ions more frequently than zinc.

Thus, zinc is unable to take the position of the magnesium ions in the molecule.
As zinc oxidizes, silver in silver nitrate will be replaced by zinc. It will become less Ag⁺.