JEE Main 2026 — Chemistry Physical Chemistry

2026mcqeasy

For a closed circuit Daniell cell, which of the following plots is the accurate one at a given temperature?

Official previous-year question

Held on 21 Jan 2026 · Verified 6 Jul 2026.

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The standard cell potential $E^\circ_{cell}$ is a thermodynamic property defined for a cell under standard conditions (concentrations of all species at $1\text{ M}$ , pressure at $1\text{ bar}$ , and a specific temperature).

For a Daniell cell, the reaction is $Zn(s) + Cu^{2+}(aq) \rightarrow Zn^{2+}(aq) + Cu(s)$ .

The standard cell potential is given by $E^\circ_{cell} = E^\circ_{Cu^{2+}/Cu} - E^\circ_{Zn^{2+}/Zn}$ .

Since $E^\circ_{cell}$ depends only on the nature of the electrodes, the nature of the electrolytes, and the temperature, it remains constant over time as long as the temperature is constant.

While the actual cell potential $E_{cell}$ changes as the reaction proceeds (due to changes in concentration according to the Nernst equation), the standard cell potential $E^\circ_{cell}$ is a constant value.

Therefore, the plot of $E^\circ_{cell}$ versus time is a horizontal line parallel to the time axis.

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JEE Main 2026 — Chemistry Physical Chemistry

2026mcqeasy

For a closed circuit Daniell cell, which of the following plots is the accurate one at a given temperature?

Official previous-year question

Held on 21 Jan 2026 · Verified 6 Jul 2026.

Options

Did you get this right?

Solution

For a Daniell cell, the reaction is $Zn(s) + Cu^{2+}(aq) \rightarrow Zn^{2+}(aq) + Cu(s)$ .

The standard cell potential is given by $E^\circ_{cell} = E^\circ_{Cu^{2+}/Cu} - E^\circ_{Zn^{2+}/Zn}$ .

Since $E^\circ_{cell}$ depends only on the nature of the electrodes, the nature of the electrolytes, and the temperature, it remains constant over time as long as the temperature is constant.

Therefore, the plot of $E^\circ_{cell}$ versus time is a horizontal line parallel to the time axis.

JEE Main 2026 — Chemistry Physical Chemistry

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JEE Main 2026 — Chemistry Physical Chemistry

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JEE Main Physical Chemistry in other years

More JEE Main Physical Chemistry questions

Other Chemistry topics for JEE Main

Organic Chemistry

Inorganic Chemistry

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