Electrochemistry – JEE Main Previous Year Questions with Solutions
JEE Main Previous Year Papers Questions of Chemistry with Solutions are available at eSaral. Practicing JEE Main chapter wise questions of Chemistry will help the JEE aspirants in realizing the question pattern as well as help in analyzing weak & strong areas.   Simulator   Previous Years AIEEE/JEE Mains Questions
Q. Given : $\mathrm{E}_{\mathrm{Fe}^{-3} / \mathrm{Fe}}^{\circ}=-0.036 \mathrm{V}, \quad \mathrm{E}_{\mathrm{Fe}^{-2} / \mathrm{Fe}}^{\circ}=-0.439 \mathrm{V}$. The value of standard electrode potential for the change. $\mathrm{Fe}^{+3}_{(\mathrm{aq})}+\mathrm{e}^{-} \longrightarrow \mathrm{Fe}^{+2}_{(\mathrm{aq})}$ will be :- (1) 0.770 V (2) –0.27 V (3) –0.072 V (4) 0.385 V AIEEE 2009

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Sol. (1) $\mathrm{E}^{\circ}=\frac{3 \times-0.036+2 \times 0.439}{1}=0.77 \Rightarrow \mathrm{A}$

Q. The Gibbs energy for the decomposition of $\mathrm{Al}_{2} \mathrm{O}_{3}$ at $500^{\circ} \mathrm{C}$ is as follows : $\frac{2}{3} \mathrm{Al}_{2} \mathrm{O}_{3} \longrightarrow \frac{4}{3} \mathrm{Al}+\mathrm{O}_{2}, \mathrm{AG}=+966 \mathrm{KJ} \mathrm{mol}^{-1}$ The potential difference needed for electrolytic reduction of $\mathrm{Al}_{2} \mathrm{O}_{3}$ at $500^{\circ} \mathrm{C}$ is at least :- (1) 5.0 V      (2) 4.5 V       (3) 3.0 V         (4) 2.5 V AIEEE 2010

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Sol. (4) $966 \times 10^{3}=4 \times 96500 \times \mathrm{E} \Rightarrow \mathrm{E}=2.5 \mathrm{V}$

Q. Resistance of 0.2 M solution of an electrolyte is $50 \Omega$. The specific conductance of the solution is 1.3 S $\mathrm{m}^{-1}$. If resistance of the 0.4M solution of the same electrolyte is $260 \Omega$, its molar conductivity is :- (1) $6250 \mathrm{Sm}^{2} \mathrm{mol}^{-1}$ (2) $6.25 \times 10^{-4} \mathrm{S} \mathrm{m}^{2} \mathrm{mol}^{-1}$ (3) $625 \times 10^{-4} \mathrm{S} \mathrm{m}^{2} \mathrm{mol}^{-1}$ (4) $62.5 \mathrm{S} \mathrm{m}^{2} \mathrm{mol}^{-1}$ AIEEE 2011/JEE-MAIN 2014

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Sol. (2) Q. The reduction potential of hydrogen half-cell will be negative if :- (1) $\mathrm{p}\left(\mathrm{H}_{2}\right)=2 \operatorname{atm}\left[\mathrm{H}^{+}\right]=1.0 \mathrm{M}$ (2) $\mathrm{p}\left(\mathrm{H}_{2}\right)=2$ atm and $\left[\mathrm{H}^{+}\right]=2.0 \mathrm{M}$ (3) $\mathrm{p}\left(\mathrm{H}_{2}\right)=1$ atm and $\left[\mathrm{H}^{+}\right]=2.0 \mathrm{M}$ (4) $\mathrm{p}\left(\mathrm{H}_{2}\right)=1$ atm and $\left[\mathrm{H}^{+}\right]=1.0 \mathrm{M}$ AIEEE 2011

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Sol. (1) Q. The standard reduction potentials for $\mathrm{Zn}^{2+} / \mathrm{Zn}, \mathrm{Ni}^{2+} / \mathrm{Ni}$ and $\mathrm{Fe}^{2+} / \mathrm{Fe}$ are $-0.76,-0.23$ and – 0.44 V respectively. The reaction $\mathrm{X}+\mathrm{Y}^{+2} \rightarrow \mathrm{X}^{2+}+\mathrm{Y}$ will be spontaneous when (1) X = Zn, Y = Ni (2) X = Ni, Y = Fe (3) X = Ni, Y = Zn (4) X = Fe, Y = Zn

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Sol. (1) For spontaneous reaction $\mathrm{E}^{\circ}>0 \mathrm{so}(\mathrm{A})$

Q. Given : Based on the data given above, strongest oxidising agent will be : (1) Cl– (2) $\mathrm{Cr}^{3+}$ (3) $\mathrm{Mn}^{2+}$ (4) $\mathrm{MnO}_{4}^{-}$ JEE-Mains 2013

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Sol. (4) Higher the SRP, stronger will be oxidising agent Hence, $\mathrm{MnO}_{4}^{-}$ is stronger oxidising agent.

Q. The equivalent conductance of NaCl at concentration C and at infinite dilution are $\lambda_{\mathrm{C}}$ and $\lambda_{\infty}$ , respectively. The correct relationship between $\lambda_{\mathrm{C}}$ and $\lambda_{\infty}$ is given as: (1) $\lambda_{\mathrm{C}}=\lambda_{\infty}-(\mathrm{B}) \sqrt{\mathrm{C}}$ (2) $\lambda_{\mathrm{C}}=\lambda_{\infty}+(\mathrm{B}) \sqrt{\mathrm{C}}$ (3) $\lambda_{\mathrm{C}}=\lambda_{\infty}+(\mathrm{B}) \mathrm{C}$ (4) $\lambda_{\mathrm{C}}=\lambda_{\infty}-(\mathrm{B}) \mathrm{C}$ JEE-Mains 2014

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Sol. (1) Fact

Q. At 298 K, the standard reduction potentials are 1.51 V for $\mathrm{MnO}_{4}-| \mathrm{Mn}^{2+}$ , 1.36 V for $\mathrm{Cl}_{2} | \mathrm{Cl}^{-}$, 1.07 V for $\mathrm{Br}_{2} | \mathrm{Br}^{-},$ and $0.54 \mathrm{V}$ for $\mathrm{I}_{2} | \mathrm{I}^{-} .$ At $\mathrm{pH}=3$, permanganate is expected to oxidize $\left(\frac{\mathrm{RT}}{\mathrm{F}}=0.059 \mathrm{V}\right):-$ (1) $\mathrm{Cl}^{-}$ and $\mathrm{Br}^{-}$ (2) $\mathrm{Cl}^{-}, \mathrm{Br}^{-}$ and $\mathrm{I}^{-}$ (3) $\mathrm{Br}^{-}$ and $\mathrm{I}^{-}$ (4) I- only JEE-Mains (online) 2015

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Sol. (3) Q. A variable, opposite external potential $\left(\mathrm{E}_{\mathrm{ext}}\right)$ is applied to the cell $\mathrm{Zn}\left|\mathrm{Zn}^{2+}(1 \mathrm{M}) \| \mathrm{Cu}^{2+}(1 \mathrm{M})\right| \mathrm{Cu}$, of potential 1.1 V. When $\mathrm{E}_{\mathrm{ext}}<1.1 \mathrm{V}$ and $\mathrm{E}_{\mathrm{ext}}>1.1 \mathrm{V}$ , respectively electrons flow from : (1) anode to cathode in both cases (2) anode to cathode and cathode to anode (3) cathode to anode in both cases (4) cathode to anode and anode to cathode JEE-Mains (online) 2015

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Sol. (2) Fact

Q. Two Faraday of electricity is passed through a solution of $\mathrm{CuSO}_{4}$. The mass of copper deposited at the cathode is : (at. mass of Cu = 63.5 amu) (1) 2g         (2) 127 g          (3) 0 g          (4) 63.5 g JEE-Mains 2015

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Sol. (4) $2 \mathrm{F}=2 \mathrm{eq}=1$ mole $=63.5 \mathrm{gm}$

Q. Galvanization is applying a coating of :- (1)Zn         (2) Pb         (3) Cr        (4) Cu JEE-Mains 2016

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Sol. (1) Galvanization is the process of applying a protective zinc coating of steel or iron, to prevent rusting.

Q. Given (1)Cr (2) $\mathrm{Mn}^{2+}$ (3) $\mathrm{Cr}^{3+}$ (4) $\mathrm{Cl}^{-}$ JEE-Mains 2017

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Sol. (1) Since $\mathrm{Cr}^{+3}$ is having least reducing potential, so Cr is the best Reducing agent.

Q. How long (approximate) should water be electrolysed by passing through 100 amperes current so that the oxygen released can completely burn 27.66 g of diborane ? (Atomic weight of B = 10.8 u) (1)0.8 hours (2) 3.2 hours (3) 1.6 hours (4) 6.4 hours JEE-Mains 2018

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Sol. (2) • June 12, 2021 at 11:33 am

Plz provide 2019 and 2020 questions. And more detail solution is required.

3
• July 24, 2021 at 10:51 pm

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3
• January 7, 2021 at 12:10 pm

can u plz post more questions for preparation

20
• December 30, 2020 at 4:25 pm

3rd question is full of mistakes…………………………………

6
• December 18, 2020 at 10:28 am

need more questions and more detailed solutions on every problem.
questions are good enough

5
• October 10, 2020 at 11:34 am

more questions and latest questions

1
• September 12, 2020 at 2:29 pm

Need detailed solutions

0
• August 30, 2020 at 8:03 pm

Thanks

0
• August 28, 2020 at 3:58 pm

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0
• August 22, 2020 at 4:35 pm

2
• August 20, 2020 at 8:19 pm

Still more questions are required plz add questions of 2019 and 20 questions in it…. And also provide detail solutions

1
• August 16, 2020 at 10:55 pm

Sir , I want to purchase previous years IIT JEE Chapter wise. Chemistry Questions with solution, you have any book for this pl confirm & cost of book

0
• August 3, 2020 at 6:52 pm

0
• July 15, 2020 at 3:45 pm

Plz bro questions are dope but i need clr solutions even i cant solve it

0
• July 2, 2020 at 7:54 pm

clear solutions required

0
• June 22, 2020 at 7:44 am

Clear solutions required

0
• June 22, 2020 at 7:44 am

Clear solutions required

0
• June 21, 2020 at 2:32 pm

Need more questions for practice

0
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1
• May 31, 2020 at 3:12 pm

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1
• May 22, 2020 at 6:55 pm

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1
• May 9, 2020 at 11:01 pm

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1
• March 23, 2020 at 6:43 am

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0
• March 23, 2020 at 6:42 am

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1