The approximate time duration in hours to electroplate $30 \ g$ of calcium from molten calcium chloride using a current of $5 \ A$ is [At. mass of $Ca=40$]

The quantity of electricity (in $C$) required to oxidize $1 \ mol$ of $H_2O$ to $O_2$ is approximately ..................... $\times 10^5 \ C$.

$A$ solution of copper sulphate $(CuSO_4)$ is electrolysed for $10 \, \text{minutes}$ with a current of $1.5 \, \text{amperes}$. The mass of copper deposited at the cathode (atomic mass of $Cu = 63 \, u$) is ............ $g$.

On passing a current through $KCl$ solution,$19.5 \ g$ of potassium is deposited. If the same quantity of electricity is passed through a solution of aluminium chloride,the amount of aluminium deposited is ............ $g$

$5 \ A$ current is passed through $AgNO_3$ solution for $193 \ s$. If $0.972 \ g$ of $Ag$ is deposited,calculate the current efficiency (cell capacity) of the electrolytic cell. $[Ag = 108 \ u]$ (in $\%$)

What is achieved by Faraday using the principles of electrolysis?