Electrochemistry · JEE Main previous year questions

2025 13 questions

1. Q562025 · 4 Apr 2025 · Shift 1

   On charging the lead storage battery, the oxidation state of lead changes from $x_1$ to $y_1$ at the anode and from $x_2$ to $y_2$ at the cathode. The values of $x_1,y_1,x_2,y_2$ are respectively :

   1. A.$0,+2,+4,+2$
   2. B.$+2,0,0,+4$
   3. C.$+4,+2,0,+2$
   4. D.$+2,0,+2,+4$
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   Answer: D

2. Q682025 · 3 Apr 2025 · Shift 1

   Correct order of limiting molar conductivity for cations in water at $298\mathrm{K}$ is :

   1. A.${\mathrm{H}}^{+}>{\mathrm{Na}}^{+}>{\mathrm{K}}^{+}>{\mathrm{Ca}}^{2+}>{\mathrm{Mg}}^{2+}$
   2. B.${\mathrm{H}}^{+}>{\mathrm{Ca}}^{2+}>{\mathrm{Mg}}^{2+}>{\mathrm{K}}^{+}>{\mathrm{Na}}^{+}$
   3. C.${\mathrm{Mg}}^{2+}>{\mathrm{H}}^{+}>{\mathrm{Ca}}^{2+}>{\mathrm{K}}^{+}>{\mathrm{Na}}^{+}$
   4. D.${\mathrm{H}}^{+}>{\mathrm{Na}}^{+}>{\mathrm{Ca}}^{2+}>{\mathrm{Mg}}^{2+}>{\mathrm{K}}^{+}$
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   Answer: B

3. Q662025 · 3 Apr 2025 · Shift 2

   The standard cell potential $\left({\mathrm{E}}_{\mathrm{cell}}^{\ominus }\right)$ of a fuel cell based on the oxidation of methanol in air that has been used to power television relay station is measured as $1.21\mathrm{V}$. The standard half cell reduction potential for ${\mathrm{O}}_2$ $\left({\mathrm{E}}_{{\mathrm{O}}_2/{\mathrm{H}}_2\mathrm{O}}^{\circ }\right)$ is $1.229\mathrm{V}$. Choose the correct statement :

   1. A.Reactants are fed at one go to each electrode.
   2. B.Oxygen is formed at the anode.
   3. C.The standard half cell reduction potential for the reduction of ${\mathrm{CO}}_2$ $\left({\mathrm{E}}_{{\mathrm{CO}}_2/{\mathrm{CH}}_3\mathrm{OH}}^{\circ }\right)$ is $19\mathrm{mV}$
   4. D.Reduction of methanol takes place at the cathode.
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   Answer: C

4. Q692025 · 3 Apr 2025 · Shift 2
   
   1. A.The concentration of ${\mathrm{CH}}_3\mathrm{COOH}$ in the original mixture is $0.005\mathrm{M}$
   2. B.The concentration of $\mathrm{HCl}$ in the original mixture is $0.005\mathrm{M}$
   3. C.${\mathrm{CH}}_3\mathrm{COOH}$ is neutralised first followed by neutralisation of $\mathrm{HCl}$
   4. D.Point ' C ' indicates the complete neutralisation of $\mathrm{HCl}$
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   Answer: B

5. Q732025 · 2 Apr 2025 · Shift 1· Numerical answer
   
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   Answer: 6

6. Q742025 · 2 Apr 2025 · Shift 2· Numerical answer

   $0.2\%(w/v)$ solution of $\mathrm{NaOH}$ is measured to have resistivity $870.0\mathrm{m\Omega }\mathrm{m}$. The molar conductivity of the solution will be ____ $\times 10^2\mathrm{mS}\mathrm{d}{\mathrm{m}}^2\mathrm{mo}{\mathrm{l}}^{-1}$. (Nearest integer)

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   Answer: 23

7. Q592025 · 29 Jan 2025 · Shift 2

   Match List - I with List - II : $$\begin{array}{ll}\text{List - I (Applications)}& \text{List - II (Batteries/Cell)}\\ \text{(A) Transistors}& \text{(I) Anode - Zn/Hg; Cathode - HgO + C}\\ \text{(B) Hearing aids}& \text{(II) Hydrogen fuel cell}\\ \text{(C) Inverters}& \text{(III) Anode - Zn; Cathode - Carbon}\\ \text{(D) Apollo space ship}& \text{(IV) Anode - Pb; Cathode - Pb | }\mathrm{Pb}{\mathrm{O}}_2\end{array}$$ Choose the correct answer from the options given below :

   1. A.(A)-(III), (B)-(I), (C)-(IV), (D)-(II)
   2. B.(A)-(II), (B)-(III), (C)-(IV), (D)-(I)
   3. C.(A)-(IV), (B)-(III), (C)-(II), (D)-(I)
   4. D.(A)-(III), (B)-(II), (C)-(IV), (D)-(I)
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   Answer: A

8. Q702025 · 29 Jan 2025 · Shift 2

   ${\mathrm{O}}_2$ gas will be evolved as a product of electrolysis of : (A) an aqueous solution of $\mathrm{AgN}{\mathrm{O}}_3$ using silver electrodes. (B) an aqueous solution of $\mathrm{AgN}{\mathrm{O}}_3$ using platinum electrodes. (C) a dilute solution of ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ using platinum electrodes. (D) a high concentration solution of ${\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ using platinum electrodes. Choose the correct answer from the options given below :

   1. A.(B) and (C) only
   2. B.(B) and (D) only
   3. C.(A) and (D) only
   4. D.(A) and (C) only
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   Answer: A

9. Q742025 · 28 Jan 2025 · Shift 1· Numerical answer
   
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   Answer: 150

10. Q682025 · 24 Jan 2025 · Shift 1

    For the given cell $\mathrm{F}{\mathrm{e}}^{2+}(\mathrm{aq})+\mathrm{A}{\mathrm{g}}_{(\mathrm{aq})}^{+}\to \mathrm{F}{\mathrm{e}}^{3+}(\mathrm{aq})+\mathrm{A}{\mathrm{g}}_{(\mathrm{s})}$ The standard cell potential of the above reaction is Given: $\mathrm{A}{\mathrm{g}}^{+}+{\mathrm{e}}^{-}\to \mathrm{Ag}{\mathrm{E}}^{\theta }=\mathrm{xV}$ $\mathrm{F}{\mathrm{e}}^{2+}+2{\mathrm{e}}^{-}\to \mathrm{Fe}{\mathrm{E}}^{\theta }=\mathrm{yV}$ $\mathrm{F}{\mathrm{e}}^{3+}+3{\mathrm{e}}^{-}\to \mathrm{Fe}{\mathrm{E}}^{\theta }=\mathrm{zV}$

    1. A.$x+2y-3z$
    2. B.$x+2y$
    3. C.$y-2x$
    4. D.$x+y-z$
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    Answer: A

11. Q642025 · 23 Jan 2025 · Shift 2

    Standard electrode potentials for a few half cells are mentioned below : ${\mathrm{E}}_{\mathrm{C}{\mathrm{u}}^{2+}/Cu}^{\circ }=0.34\mathrm{V}$, ${\mathrm{E}}_{\mathrm{Z}{\mathrm{n}}^{2+}/Zn}^{\circ }=-0.76\mathrm{V}$ ${\mathrm{E}}_{\mathrm{A}{\mathrm{g}}^{+}/Ag}^{\circ }=0.80\mathrm{V}$, ${\mathrm{E}}_{\mathrm{M}{\mathrm{g}}^{2+}/Mg}^{\circ }=-2.37\mathrm{V}$ Which one of the following cells gives the most negative value of $\Delta {\mathrm{G}}^{\circ }$ ?

    1. A.$Zn|Z{\mathrm{n}}^{2+}(1M)||A{\mathrm{g}}^{+}(1M)|Ag$
    2. B.$Ag|A{\mathrm{g}}^{+}(1M)||M{\mathrm{g}}^{2+}(1M)|Mg$
    3. C.$Zn|Z{\mathrm{n}}^{2+}(1M)||M{\mathrm{g}}^{2+}(1M)|Mg$
    4. D.$Cu|C{\mathrm{u}}^{2+}(1M)||A{\mathrm{g}}^{+}(1M)|Ag$
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    Answer: A

12. Q512025 · 22 Jan 2025 · Shift 1

    Which of the following electrolyte can be used to obtain ${\mathrm{H}}_2{\mathrm{S}}_2{\mathrm{O}}_8$ by the process of electrolysis ?

    1. A.Concentrated solution of sulphuric acid
    2. B.Dilute solution of sodium sulphate.
    3. C.Acidified dilute solution of sodium sulphate.
    4. D.Dilute solution of sulphuric acid
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    Answer: A

13. Q582025 · 22 Jan 2025 · Shift 1

    A solution of aluminium chloride is electrolysed for 30 minutes using a current of 2 A . The amount of the aluminium deposited at the cathode is _________ . [Given : molar mass of aluminium and chlorine are $27{\text{ g mol}}^{-1}$ and $35.5{\text{ g mol}}^{-1}$ respectively. Faraday constant $=96500{\text{ C mol}}^{-1}$]

    1. A.$1.660\text{ g}$
    2. B.$1.007\text{ g}$
    3. C.$0.336\text{ g}$
    4. D.$0.441\text{ g}$
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    Answer: C