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

What is electrochemistry? Give the uses of electrochemistry.

Hydrogen-oxygen fuel cells are used in spacecraft to supply:

Select the incorrect statement for a dry cell.

When a $Cu$ rod is kept in an $AgNO_3$ solution,what is the redox reaction that occurs?

Calculate $\Delta G^{\circ}$ for the reaction $Mg_{(s)} + Sn_{(aq)}^{2+} \longrightarrow Mg_{(aq)}^{2+} + Sn_{(s)}$ if $E_{cell}^{\circ}$ is $2.23 \ V$. (in $kJ$)