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.
Assertion (A) Copper sulphate can be stored in zinc vessel.
Reason (R) Zinc is less reactive than copper.
Consider the figure and answer the following questions.
(i) Cell ' $A$ ' has $\mathrm{E}_{\text {cell }}=2 \mathrm{~V}$ and Cell ' B ' has $\mathrm{E}_{\text {cell }}=1.1 \mathrm{~V}$ which of the two cells 'A' or 'B' will act as an electrolytic cell. Which electrode reactions will occur in this cell?
(ii) If cell ' $A$ ' has $\mathrm{E}_{\text {cell }}=0.5 \mathrm{~V}$ and cell ' $B^{\prime}$ has $\mathrm{E}_{\text {cell }}=1.1 \mathrm{~V}$ then what will be the reactions at anode and cathode?
(i) Cell ' $B$ ' will act as electrolytic cell due to its lesser value of emf.
The electrode reactions will be
At cathode $$\quad\mathrm{Zn}^{2+}+2 e^{-} \longrightarrow \mathrm{Zn}$$
At anode $$\quad \mathrm{Cu} \longrightarrow \mathrm{Cu}^{2+}+2 e^{-}$$
(ii) If cell ' $B$ ' has higher emf, it acts as galvanic cell.
Now it will push electrons into cell ' $A$ '
In this case, the reactions will be
$$\begin{aligned} \mathrm{Zn} & \longrightarrow \mathrm{Zn}^{2+}+2 \mathrm{e}^{-} \text {(At anode) } \\ \mathrm{Cu}^{2+}+2 e^{-} & \longrightarrow \mathrm{Cu} \text { (At cathode) } \end{aligned}$$