Consider the above electrochemical cell where a metal electrode (M) is undergoing redox reaction by forming $\mathrm{M}^{+}$ ($\mathrm{M} \rightarrow \mathrm{M}^{+}+\mathrm{e}$). The cation $\mathrm{M}^{+}$ is present in two different concentrations $\mathrm{c}_{1}$ and $\mathrm{c}_{2}$ as shown above. Which of the following statement is correct for generating a positive cell potential?

(C) If $\mathrm{c}_{1}$ is present at cathode, then $\mathrm{c}_{1}>\mathrm{c}_{2}$

(A) If $\mathrm{c}_{1}$ is present at anode, then $\mathrm{c}_{1}=\mathrm{c}_{2}$

(B) If $\mathrm{c}_{1}$ is present at cathode, then $\mathrm{c}_{1}<\mathrm{c}_{2}$

(D) If $c_{1}$ is present at anode, then $c_{1}>c_{2}$

JEE Main · 2026 · 23 Jan 2026 · Shift 2 · Redox Reactions and Electrochemistry

Consider the above electrochemical cell where a metal electrode (M) is undergoing redox reaction by forming

M^{+}

(

M \to M^{+} + e

). The cation

M^{+}

is present in two different concentrations

c_{1}

and

c_{2}

as shown above. Which of the following statement is correct for generating a positive cell potential?

Answer: (C)

In this concentration cell both electrodes are the same metal, so the standard cell potential is zero and the Nernst equation reduces to

E_{ce l l} = - \frac{0.059}{1} lo g \frac{[ M ^{+} ] _{anode}}{[ M ^{+} ] _{cathode}}

. A positive

E_{ce l l}

requires the logarithm to be negative, which means the cathode compartment must be the more concentrated one. Taking

c_{1}

as the cathode concentration and

c_{2}

as the anode concentration, the cell delivers a positive potential only when

c_{1} > c_{2}

JEE Main · 2026 · 23 Jan 2026 · Shift 2 · Single correct option