Which substance is reduced in a dry cell?

What is an electrode and a half-cell? Explain their symbolic representation with a suitable example.

Depict the galvanic cell in which the cell reaction is: $Cu + 2Ag^{+} \to 2Ag + Cu^{2+}$

Write the reactions for the following:
$1.$ Oxidation and reduction reactions of a lead storage cell.
$2.$ Cell reaction of a $Ni-Cd$ cell.
$3.$ Anode,cathode,and overall reaction of a mercury cell.

Fill in the blanks :
$1.$ $E_{cell}^o$ of Daniell cell $= $ ........... .
$2.$ In Daniell cell,$n = $ ........... .
$3.$ For $Al + 3Ag^{+} \rightarrow Al^{3+} + 3Ag,$ $n = $ ...........

Which of the following is used to avoid leakage of electrolyte in a dry cell?