![JEE Main 2026 Chemistry, Electrochemistry — question figure](https://prepforbharat.s3.ap-south-1.amazonaws.com/exam/615f0e999476412f48314daf/Chemistry/images/Electrochemistry/6983c19b8bfdbb24356396dd/question_1__q_6983c19b8bfdbb24356396dd__cdn-question-pool.getmarks.app__23S2_q_55_1_v2__27ea52b964_final_ppt_sync.png) Consider the above electrochemical cell where a metal electrode (M) is undergoing redox reaction by forming $\mathrm{M}^{+}\left(\mathrm{M} \rightarrow \mathrm{M}^{+}+\mathrm{e}^{-}\right)$. The cation $\mathrm{M}^{+}$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?

JEE Main 2026 — Chemistry Physical Chemistry

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JEE Main 2026 Chemistry, Electrochemistry — question figure

Consider the above electrochemical cell where a metal electrode (M) is undergoing redox reaction by forming $\mathrm{M}^{+}\left(\mathrm{M} \rightarrow \mathrm{M}^{+}+\mathrm{e}^{-}\right)$ . The cation $\mathrm{M}^{+}$ 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?

Official previous-year question

Held on 23 Jan 2026 · Verified 6 Jul 2026.

Options

A
If $\mathrm{c}_{1}$ is present at cathode, then $\mathrm{c}_{1}<\mathrm{c}_{2}$ .
B
If $\mathrm{c}_{1}$ is present at anode, then $\mathrm{c}_{1}>\mathrm{c}_{2}$ .
C
If $c_{1}$ is present at cathode, then $c_{1}>c_{2}$ .
D
If $\mathrm{c}_{1}$ is present at anode, then $\mathrm{c}_{1}=\mathrm{c}_{2}$ .

Did you get this right?

Solution

The given setup is a concentration cell with identical electrodes (M) and different electrolyte concentrations ( $c_1$ and $c_2$ ).

For a concentration cell, the standard cell potential $E^0_{cell} = 0$ .

The cell reactions are:

Anode: $M(s) \rightarrow M^+(c_{anode}) + e^-$

Cathode: $M^+(c_{cathode}) + e^- \rightarrow M(s)$

Net reaction: $M^+(c_{cathode}) \rightarrow M^+(c_{anode})$

Using the Nernst equation at $298\text{ K}$ :

$E_{cell} = E^0_{cell} - \frac{0.0591}{n} \log \frac{c_{anode}}{c_{cathode}}$

$E_{cell} = 0 - 0.0591 \log \frac{c_{anode}}{c_{cathode}}$

For a positive cell potential ( $E_{cell} > 0$ ), the term $\log \frac{c_{anode}}{c_{cathode}}$ must be negative.

This requires $\frac{c_{anode}}{c_{cathode}} < 1$ , which means $c_{cathode} > c_{anode}$ .

If $c_1$ is present at the cathode and $c_2$ is at the anode, then for $E_{cell} > 0$ , we must have $c_1 > c_2$ .

Checking the options:

(1) If $c_1$ is at cathode, $c_1 < c_2$ (Incorrect)

(2) If $c_1$ is at anode, $c_1 > c_2$ (Incorrect, would require $c_2 > c_1$ )

(3) If $c_1$ is at cathode, $c_1 > c_2$ (Correct)

(4) If $c_1$ is at anode, $c_1 = c_2$ (Incorrect, $E_{cell}$ would be zero)

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Options

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

If $\mathrm{c}_{1}$ is present at anode, then $\mathrm{c}_{1}>\mathrm{c}_{2}$ .

If $c_{1}$ is present at cathode, then $c_{1}>c_{2}$ .

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

Solution

The given setup is a concentration cell with identical electrodes (M) and different electrolyte concentrations ( $c_1$ and $c_2$ ).

For a concentration cell, the standard cell potential $E^0_{cell} = 0$ .

The cell reactions are:

Anode: $M(s) \rightarrow M^+(c_{anode}) + e^-$

Cathode: $M^+(c_{cathode}) + e^- \rightarrow M(s)$

Net reaction: $M^+(c_{cathode}) \rightarrow M^+(c_{anode})$

Using the Nernst equation at $298\text{ K}$ :

$E_{cell} = E^0_{cell} - \frac{0.0591}{n} \log \frac{c_{anode}}{c_{cathode}}$

$E_{cell} = 0 - 0.0591 \log \frac{c_{anode}}{c_{cathode}}$

For a positive cell potential ( $E_{cell} > 0$ ), the term $\log \frac{c_{anode}}{c_{cathode}}$ must be negative.

This requires $\frac{c_{anode}}{c_{cathode}} < 1$ , which means $c_{cathode} > c_{anode}$ .

If $c_1$ is present at the cathode and $c_2$ is at the anode, then for $E_{cell} > 0$ , we must have $c_1 > c_2$ .

Checking the options:

(1) If $c_1$ is at cathode, $c_1 < c_2$ (Incorrect)

(2) If $c_1$ is at anode, $c_1 > c_2$ (Incorrect, would require $c_2 > c_1$ )

(3) If $c_1$ is at cathode, $c_1 > c_2$ (Correct)

(4) If $c_1$ is at anode, $c_1 = c_2$ (Incorrect, $E_{cell}$ would be zero)

JEE Main 2026 — Chemistry Physical Chemistry

Options

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Solution

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JEE Main 2026 — Chemistry Physical Chemistry

Options

Did you get this right?

Solution

Your note

JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

Keep practicing Physical Chemistry