Which of the following changes takes place at the positive electrode during the recharging of a lead accumulator?

Observe the following statements about a dry cell:
$I$. It is a primary battery.
$II$. Zinc vessel acts as cathode.
$III$. $A$ paste of moist $NH_4Cl$,$MnO_2$ and $ZnCl_2$ is present between two electrodes.
$IV$. The potential of this cell is $1.5 \ V$.
The correct statements are:

In $H_2-O_2$ fuel cell,the reaction occurring at the cathode is:

In an electrochemical cell,

$A$ cell reaction is spontaneous when

Which among the following is an example of a metal-sparingly soluble salt electrode?