The number of coulombs required to reduce $12.3 \ g$ of nitrobenzene to aniline is:

Cells $A$ and $B$ contain aqueous solutions of ferrous chloride $(FeCl_2)$ and ferric chloride $(FeCl_3)$ respectively. If the same quantity of electricity is passed through both cells, what is the ratio of the mass of iron deposited in cell $A$ to that in cell $B$?

If $96500 \ C$ of electricity liberates one gram equivalent of any substance,the time taken for a current of $0.15 \ A$ to deposit $20 \ mg$ of copper from a solution of copper sulphate is (Chemical equivalent of copper = $32$).

The electrochemical equivalent of a metal is $3.3 \times 10^{-7} \ kg/C$. The mass of the metal liberated at the cathode when a $3 \ A$ current is passed for $2 \ s$ will be:

$A$ current of $16\, A$ flows through molten $NaCl$ for $10\, min$. The amount of metallic sodium that appears at the negative electrode would be ............ $g$.

Faraday's laws of electrolysis will fail when