NEET UG Unit 9A: Redox Processes & Electrochemical Cells — practice questions

Check oxidation states. A reaction is not redox if there is no change in oxidation number. In option $\mathrm{A}$, the process is essentially ionization of $\mathrm{HCl}$ in water. The oxidation numbers of $\mathrm{H}$ and $\mathrm{Cl}$ do not change so it is not a redox reaction. In option $\mathrm{B}$, $\mathrm{Zn}$ goes from $0$ to $+2$ and $\mathrm{Cu}^{2+}$ goes from $+2$ to $0$, so it is redox. In option $\mathrm{C}$, $\mathrm{H}$ goes from $0$ to $+1$ and $\mathrm{O}$ goes from $0$ to $-2$, so it is redox. In option $\mathrm{D}$, sulfur in $\mathrm{SO}_2$ goes from $+4$ to $+6$ and chlorine in $\mathrm{Cl}_2$ goes from $0$ to $-1$, so it is redox. Therefore, the reaction which is not redox is option $\mathrm{A}$.

In electrolysis of $\mathrm{CuSO_4}$, copper is deposited at the cathode, not at the anode. At the anode, oxidation occurs so no copper gets deposited there. Therefore, the gram equivalent of copper deposited on anode is $0$. Among the options, $\mathrm{Zero}$ matches this result.

At infinite dilution, ionic molar conductivity depends on ionic mobility in water. Among common cations, $\mathrm{H^+}$ has exceptionally high mobility because it moves through the hydrogen-bonded network of water by proton hopping. So the highest limiting molar conductivity is for $\mathrm{H^+}$. Final check against the options: $\mathrm{Na^+}$, $\mathrm{K^+}$, $\frac{1}{2}\mathrm{Ca^{2+}}$, and $\mathrm{H^+}$. The matching option is $\mathrm{H^+}$, which is option $\mathrm{D}$.