The reaction occurs in which of the given galvanic cell? (1)/(2) H...

Oxidation is loss of electron and in a galvanic cell it occurs at anode. Reduction is gain of electron and in a galvanic cell it occurs at cathode.

At anode :$\dfrac{1}{2}{H}_{2} ( g ) ⟶ \mathop{{H}^{+}}_{( aq )} + {e}^{-}$

At cathode $\mathop{AgCl}_{( S )} + \overset{¯}{e} ⟶ Ag + \mathop{{Cl}^{-}}_{\text{(aq)}}$

Overall reaction

$\dfrac{1}{2}{H}_{2} ( g ) + AgCl ( s ) ⟶ {H}^{*} + {Cl}^{-} + Ag ( s )$

Cell representation :

Anode / Anode electrolyte || Cathodic electrolyte / Cathode.

The cell representation for the above cell will be

$Pt\left|{H}_{2} ( g )\right|HCl\left({\text{soln}}^{n}\right) | AgCl ( s ) | Ag$