What are the uses of the $Ni-Cd$ cell?

$A$ lead storage battery is discharged. During the charging of this battery,the reaction that occurs at the anode is:

Which option is incorrect for the working cell? $Pt \mid Cl_{2(g, 1 \ bar)} \mid Cl_{(C_1)}^{-} \parallel Cl_{(C_2)}^{-} \mid Cl_{2(g, 1 \ bar)} \mid Pt$

Given the standard electrode potentials $E^{0}_{Fe^{2+}|Fe} = -0.44 \, V$ and $E^{0}_{Fe^{3+}|Fe^{2+}} = 0.77 \, V$. If $Fe^{2+}$,$Fe^{3+}$,and $Fe$ are all present together,then:

$A$ solution containing $1 \ mol \ L^{-1}$ of each $Cu(NO_3)_2, AgNO_3, Hg_2(NO_3)_2$ and $Mg(NO_3)_2$ is being electrolysed using inert electrodes. The standard reduction potentials are $E^0_{Ag^{+}/Ag} = +0.80 \ V, E^0_{Hg_2^{2+}/Hg} = +0.79 \ V, E^0_{Cu^{2+}/Cu} = +0.34 \ V, E^0_{Mg^{2+}/Mg} = -2.37 \ V$. With increasing voltage,the sequence of deposition of metals on the cathode will be:

Give True $(T)$ or False $(F)$ :
$1.$ $H_2$ is used as fuel in fuel cell.
$2.$ Thermal plants are more pollutants as compared to fuel cell.
$3.$ Fuel cell is pollution free.