Assertion (A) Mercury cell does not give steady potential.

Reason (R) In the cell reaction, ions are not involved in solution.

Assertion (A) Electrolysis of NaCl solution gives chlorine at anode instead of $\mathrm{O}_2$.

Reason $(R)$ Formation of oxygen at anode requires over voltage.

Assertion (A) For measuring resistance of an ionic solution an AC source is used.

Reason (R) Concentration of ionic solution will change if DC source is used.

Assertion (A) Current stops flowing when $\mathrm{E}_{\text {cell }}=0$.

Reason (R) Equilibrium of the cell reaction is attained.

Assertion (A) $\mathrm{E}_{\mathrm{Ag}^{+} / \mathrm{Ag}}$ increase with increase in concentration of $\mathrm{Ag}^{+}$ ions.

Reason $(R) \mathrm{E}_{\mathrm{Ag}^{+} / \mathrm{Ag}}$ has a positive value.