What acts as a reducing agent when a dry cell is working?

Select the correct cell reaction for the cell $Pt_{(s)}|Cl_{2(g)}|Cl^{-}_{(aq)}||Ag^{+}_{(aq)}|Ag_{(s)}$.

$A$ saturated solution of $KNO_3$ is used to make a salt bridge because...

The maximum work that can be obtained from the following cell is
$X|X^{2+}_{(aq)} || Y^{+}_{(aq)}| Y$
Given,$E^{\circ}_{X^{2+}/X} = -1.7 \ V, E^{\circ}_{Y^{+}/Y} = 0.8 \ V$

If the salt bridge between two half-cells is removed,the voltage of the cell:

$A$ depolarizer used in dry cell batteries is