Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 20266 AprilEvening Shift
Exam
JEE Main
Year
2026
Date
6 April
Shift
Evening Shift
Subject
Chemistry
Chapter
Electrochemistry

JEE Main 2026 · 6 April · Evening Shift · Chemistry · Electrochemistry

For a general redox reaction Anode : Red_1 arrow Ox_1^ n_1^+ + n_1...

For a general redox reaction
Anode : Red1→Ox1n1++n1e−\text{Red}_1 \rightarrow \text{Ox}_1^{n_1^+} + n_1 e^-
Cathode : Ox2+n2e−→Red2n2−\text{Ox}_2 + n_2 e^- \rightarrow \text{Red}_2^{n_2^-}
Which of the following statement is incorrect ?For a general redox reaction Anode : Red_1 arrow Ox_1^ n_1^+ + n_1 e^- Cathode : Ox_2 + n_2 e^- arrow Red_2^ n_2^-

Options

  1. AThe overall reaction can be written as n2Red1+n1Ox2⇌n2Ox1n1++n1Red2n2−n_2\text{Red}_1 + n_1\text{Ox}_2 \rightleftharpoons n_2\text{Ox}_1^{n_1^+} + n_1\text{Red}_2^{n_2^-}
  2. BThe electrons do not appear in the overall reaction because electrons produced at the anode are consumed at the cathode.
  3. CHere nn is the number of electrons transferred in redox reaction.
    Consider the following reactions in which all the reactants and products are present in gaseous state 2xy leftharpoons
  4. DIf the reaction is carried out reversibly, the electrical work done is equal to the ratio of charge and potential difference through which charge is moved.

Correct answer

D. If the reaction is carried out reversibly, the electrical work done is equal to the ratio of charge and potential difference through which charge is moved.

Step-by-step solution

For the given redox reaction, the half-cell reactions are:
Anode: Red1→Ox1n1++n1e−\text{Red}_1 \rightarrow \text{Ox}_1^{n_1^+} + n_1 e^-
Cathode: Ox2+n2e−→Red2n2−\text{Ox}_2 + n_2 e^- \rightarrow \text{Red}_2^{n_2^-}

To obtain the overall balanced chemical equation, we multiply the anode reaction by n2n_2 and the cathode reaction by n1n_1 so that the number of electrons lost equals the number of electrons gained:
n2Red1→n2Ox1n1++n1n2e−n_2\text{Red}_1 \rightarrow n_2\text{Ox}_1^{n_1^+} + n_1 n_2 e^-
n1Ox2+n1n2e−→n1Red2n2−n_1\text{Ox}_2 + n_1 n_2 e^- \rightarrow n_1\text{Red}_2^{n_2^-}

Adding these gives the overall reaction:
n2Red1+n1Ox2⇌n2Ox1n1++n1Red2n2−n_2\text{Red}_1 + n_1\text{Ox}_2 \rightleftharpoons n_2\text{Ox}_1^{n_1^+} + n_1\text{Red}_2^{n_2^-}
Thus, statement (A) is correct.

In the overall reaction, electrons do not appear because the electrons produced at the anode are exactly consumed at the cathode. Thus, statement (B) is correct.

From the Nernst equation:
E=E∘−RTnFln⁡Q=E∘−2.303RTnFlog⁡10QE = E^\circ - \dfrac{RT}{nF} \ln Q = E^\circ - \dfrac{2.303 RT}{nF} \log_{10} Q
E−E∘RT/F=−2.303nlog⁡10Q\dfrac{E - E^\circ}{RT/F} = -\dfrac{2.303}{n} \log_{10} Q
The graph of E−E∘RT/F\dfrac{E - E^\circ}{RT/F} versus log⁡10Q\log_{10} Q is a straight line with a slope of −2.303n-\dfrac{2.303}{n}, where nn is the number of electrons transferred in the balanced redox reaction. Thus, statement (C) is correct.

The electrical work done by a galvanic cell is given by the product of the total charge transferred and the cell potential (potential difference), not their ratio.
Welectrical=Charge×Potential difference=nFEcellW_{\text{electrical}} = \text{Charge} \times \text{Potential difference} = nF E_{\text{cell}}
Thus, statement (D) is incorrect.

Answer: If the reaction is carried out reversibly, the electrical work done is equal to the ratio of charge and potential difference through which charge is moved.
Practice Electrochemistry on Quantrex Academy →

More from Electrochemistry

At 300 K, the molar conductivities of the aqueous solutions of three salts at two… JEE Advanced 2026Given at 298 K: E^ _ Fe^ 2+ /Fe = X Volt; E^ _ Fe^ 3+ /Fe = Y Volt. The E^ _ Fe^ 3+ /Fe^… JEE Main 2026Consider the following data. Electrolyte Λ^ ∘ _m (S cm ^2 mol ^ -1 ) BaCl_2 x_1 H_2SO_4… JEE Main 2026One half cell in a voltaic cell is constructed by dipping silver rod in AgNO_3 solution… JEE Main 2026At 298 K , the molar conductivity of x\% (w/w) MX solution (aqueous) is 123.5 S cm^2 mol^… JEE Main 2026An electrochemical cell, consist of the following two redox couples, M^ x+ (aq)/M(s) [E_… JEE Main 2026Consider the following two half-cell reactions along with the standard reduction… JEE Main 2026An electrochemical cell is constructed using half cells in the direction of spontaneous… JEE Main 2026 Full Electrochemistry list All JEE Main PYQs