How much time is required for complete decomposition of $4 \, \text{moles}$ of water using $4 \, \text{A}$ current?

The mass of a substance liberated when a charge $q$ flows through an electrolyte is proportional to

When two electrolytic cells containing $NiSO_4$ and $CuSO_4$ solutions are connected in series and an electric current is passed,$1.6 \ g$ of $Cu$ is deposited on the electrode. How much $Ni$ metal is produced? If a cell containing $AgNO_3$ solution is connected instead of $NiSO_4$,how many grams of silver will be obtained? [Atomic mass: $Cu = 63.5 \ g/mol$,$Ni = 58.7 \ g/mol$,$Ag = 108 \ g/mol$]

$0.50 \, L$ of a $0.60 \, M$ $CuSO_4$ solution is electrolyzed for a period of $30.0 \, min$ using a current of $4.60 \, A$. If inert electrodes are used,what is the final concentration of $Cu^{2+}$ remaining in the solution? $M$

Calculate the current (in $mA$) required to deposit $0.195 \ g$ of platinum metal in $5.0 \ hours$ from a solution of $[PtCl_6]^{2-}$ : (atomic weight : $Pt = 195$)

Calculate the quantity of electricity required to liberate $0.1 \ mole$ of chlorine gas during electrolysis of molten sodium chloride. (in $C$)