Electrochemistry · JEE Main previous year questions

2023 17 questions

1. Q702023 · 12 Apr 2023 · Shift 1

   For lead storage battery pick the correct statements A. During charging of battery, $\mathrm{PbS}{\mathrm{O}}_4$ on anode is converted into $\mathrm{Pb}{\mathrm{O}}_2$ B. During charging of battery, $\mathrm{PbS}{\mathrm{O}}_4$ on cathode is converted into $\mathrm{Pb}{\mathrm{O}}_2$ C. Lead storage battery consists of grid of lead packed with $\mathrm{Pb}{\mathrm{O}}_2$ as anode D. Lead storage battery has $\sim 38\%$ solution of sulphuric acid as an electrolyte Choose the correct answer from the options given below:

   1. A.A, B, D only
   2. B.B, C only
   3. C.B, C, D only
   4. D.B, D only
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   Answer: D

2. Q892023 · 11 Apr 2023 · Shift 1· Numerical answer

   In an electrochemical reaction of lead, at standard temperature, if ${\mathrm{E}}^0\left({\mathrm{Pb}}^{2+}/\mathrm{Pb}\right)=m\text{ Volt}$ and ${\mathrm{E}}^0\left({\mathrm{Pb}}^{4+}/\mathrm{Pb}\right)=n\text{ Volt}$, then the value of ${\mathrm{E}}^0\left({\mathrm{Pb}}^{2+}/{\mathrm{Pb}}^{4+}\right)$ is given by $m-xn$. The value of $x$ is _________. (Nearest integer)

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   Answer: 2

3. Q872023 · 11 Apr 2023 · Shift 2· Numerical answer

   The number of correct statements from the following is _________ A. ${\mathrm{E}}_{\text{cell}}$ is an intensive parameter B. A negative ${\mathrm{E}}^{\ominus }$ means that the redox couple is a stronger reducing agent than the ${\mathrm{H}}^{+}/{\mathrm{H}}_2$ couple. C. The amount of electricity required for oxidation or reduction depends on the stoichiometry of the electrode reaction. D. The amount of chemical reaction which occurs at any electrode during electrolysis by a current is proportional to the quantity of electricity passed through the electrolyte.

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   Answer: 4

4. Q892023 · 10 Apr 2023 · Shift 2· Numerical answer

   The specific conductance of 0.0025 M acetic acid is $5\times 10^{-5}{\text{ S cm}}^{-1}$ at a certain temperature. The dissociation constant of acetic acid is _________ $\times 10^{-7}$ (Nearest integer) Consider limiting molar conductivity of ${\text{CH}}_3\text{COOH}$ as $400{\text{ S cm}}^2{\text{ mol}}^{-1}$

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   Answer: 66

5. Q702023 · 8 Apr 2023 · Shift 1

   The reaction $\frac{1}{2}{\mathrm{H}}_2(\mathrm{g})+\mathrm{AgCl}(\mathrm{s})\rightleftharpoons {\mathrm{H}}^{+}(\mathrm{aq})+\mathrm{C}{\mathrm{l}}^{-}(\mathrm{aq})+\mathrm{Ag}(\mathrm{s})$ occurs in which of the given galvanic cell.

   1. A.$Ag|AgCl(\mathrm{s})|KCl(\mathrm{so}{\mathrm{l}}^{\mathrm{n}})|AgN{\mathrm{O}}_3|Ag$
   2. B.$Pt|{\mathrm{H}}_2(\mathrm{g})|HCl(\mathrm{so}{\mathrm{l}}^{\mathrm{n}})|AgCl(\mathrm{s})|Ag$
   3. C.$Pt|{\mathrm{H}}_2(\mathrm{g})|HCl(\mathrm{so}{\mathrm{l}}^{\mathrm{n}})|AgN{\mathrm{O}}_3(\mathrm{so}{\mathrm{l}}^{\mathrm{n}})|Ag$
   4. D.$Pt|{\mathrm{H}}_2(\mathrm{g})|KCl(\mathrm{so}{\mathrm{l}}^{\mathrm{n}})|AgCl(\mathrm{s})|Ag$
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   Answer: B

6. Q882023 · 8 Apr 2023 · Shift 2· Numerical answer

   The number of incorrect statements from the following is ____. A. The electrical work that a reaction can perform at constant pressure and temperature is equal to the reaction Gibbs energy. B. ${\mathrm{E}}_{\mathrm{cell}}^{\circ }$ cell is dependent on the pressure. C. $\frac{\mathrm{d}{E}_{\text{cell}}^{\theta }}{\mathrm{dT}}=\frac{{\Delta }_r{S}^{\theta }}{n\mathrm{F}}$ D. A cell is operating reversibly if the cell potential is exactly balanced by an opposing source of potential difference.

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   Answer: 1

7. Q622023 · 6 Apr 2023 · Shift 1

   The standard electrode potential of ${\text{M}}^{+}/\text{M}$ in aqueous solution does not depend on

   1. A.Ionisation of a gaseous metal atom
   2. B.Sublimation of a solid metal
   3. C.Ionisation of a solid metal atom
   4. D.Hydration of a gaseous metal ion
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   Answer: C

8. Q762023 · 6 Apr 2023 · Shift 2

   The product, which is not obtained during the electrolysis of brine solution is :

   1. A.$\mathrm{NaOH}$
   2. B.$\mathrm{C}{\mathrm{l}}_2$
   3. C.${\mathrm{H}}_2$
   4. D.$\mathrm{HCl}$
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   Answer: D

9. Q822023 · 6 Apr 2023 · Shift 2· Numerical answer

   The standard reduction potentials at $298\text{ K}$ for the following half cells are given below: $$\begin{array}{rl}\mathrm{N}{\mathrm{O}}_3^{-}+4{\mathrm{H}}^{+}+3{\mathrm{e}}^{-}\to \mathrm{NO}(\mathrm{g})+2{\mathrm{H}}_2\mathrm{O}& {\mathrm{E}}^{\theta }=0.97\mathrm{V}\\ {\mathrm{V}}^{2+}(\mathrm{aq})+2{\mathrm{e}}^{-}\to \mathrm{V}& {\mathrm{E}}^{\theta }=-1.19\mathrm{V}\\ \mathrm{F}{\mathrm{e}}^{3+}(\mathrm{aq})+3{\mathrm{e}}^{-}\to \mathrm{Fe}& {\mathrm{E}}^{\theta }=-0.04\mathrm{V}\\ \mathrm{A}{\mathrm{g}}^{+}(\mathrm{aq})+{\mathrm{e}}^{-}\to \mathrm{Ag}(\mathrm{s})& {\mathrm{E}}^{\theta }=0.80\mathrm{V}\\ \mathrm{A}{\mathrm{u}}^{3+}(\mathrm{aq})+3{\mathrm{e}}^{-}\to \mathrm{Au}(\mathrm{s})& {\mathrm{E}}^{\theta }=1.40\mathrm{V}\end{array}$$ The number of metal(s) which will be oxidized by $\mathrm{N}{\mathrm{O}}_3^{-}$ in aqueous solution is ___________.

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   Answer: 3

10. Q832023 · 1 Feb 2023 · Shift 1· Numerical answer

    At what pH, given half cell ${\text{MnO}}_4^{-}(0.1\text{ M})\mid {\text{Mn}}^{2+}(0.001\text{ M})$ will have electrode potential of $1.282\text{ V}$? ________ (Nearest Integer) Given ${\text{E}}_{{\text{MnO}}_4^{-}|{\text{Mn}}^{2+}}^{\circ }=1.54\text{ V},\frac{2.303\text{RT}}{\text{F}}=0.059\text{V}$

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    Answer: 3

11. Q722023 · 31 Jan 2023 · Shift 1

    Which one of the following statements is correct for electrolysis of brine solution?

    1. A.${\mathrm{O}}_2$ is formed at cathode
    2. B.${\mathrm{H}}_2$ is formed at anode
    3. C.${\mathrm{Cl}}_2$ is formed at cathode
    4. D.${\mathrm{OH}}^{-}$ is formed at cathode
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    Answer: D

12. Q862023 · 31 Jan 2023 · Shift 2· Numerical answer

    The resistivity of a $0.8\mathrm{M}$ solution of an electrolyte is $5\times 10^{-3}\Omega \text{ cm}$. Its molar conductivity is ___________ $\times 10^4{\Omega }^{-1}{\text{ cm}}^2{\text{ mol}}^{-1}$. (Nearest integer)

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    Answer: 25

13. Q782023 · 30 Jan 2023 · Shift 1

    Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : In expensive scientific instruments, silica gel is kept in watch-glasses or in semipermeable membrane bags. Reason (R) : Silica gel adsorbs moisture from air via adsorption, thus protects the instrument from water corrosion (rusting) and / or prevents malfunctioning. In the light of the above statements, choose the correct answer from the options given below :

    1. A.Both (A) and (R) are true and (R) is the correct explanation of (A)
    2. B.(A) is true but (R) is false
    3. C.(A) is false but (R) is true
    4. D.Both (A) and (R) are true but (R) is not the correct explanation of (A)
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    Answer: A

14. Q852023 · 30 Jan 2023 · Shift 1· Numerical answer

    Consider the cell ${\mathrm{Pt}}_{(\mathrm{s})}|{\mathrm{H}}_2(\text{g},1\text{ atm})|{\mathrm{H}}^{+}(\text{aq},1\mathrm{M})||{\mathrm{Fe}}^{3+}(\text{aq}),{\mathrm{Fe}}^{2+}(\text{aq})\mid \mathrm{Pt}(\mathrm{s})$ When the potential of the cell is $0.712\text{ V}$ at $298\text{ K}$, the ratio $[{\mathrm{Fe}}^{2+}]/[{\mathrm{Fe}}^{3+}]$ is ___________. (Nearest integer) Given : ${\mathrm{Fe}}^{3+}+{\mathrm{e}}^{-}={\mathrm{Fe}}^{2+},E^0{\mathrm{Fe}}^{3+},{\mathrm{Fe}}^{2+}\mid \mathrm{Pt}=0.771$ $\frac{2.303\mathrm{RT}}{\mathrm{F}}=0.06\text{ V}$

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    Answer: 10

15. Q712023 · 29 Jan 2023 · Shift 1

    The standard electrode potential $({\mathrm{M}}^{3+}/{\mathrm{M}}^{2+})$ for V, Cr, Mn & Co are $-0.26$ V, $-0.41$ V, + 1.57 V and + 1.97 V, respectively. The metal ions which can liberate ${\mathrm{H}}_2$ from a dilute acid are :

    1. A.$\mathrm{M}{\mathrm{n}}^{2+}$ and $\mathrm{C}{\mathrm{o}}^{2+}$
    2. B.${\mathrm{V}}^{2+}$ and $\mathrm{M}{\mathrm{n}}^{2+}$
    3. C.${\mathrm{V}}^{2+}$ and $\mathrm{C}{\mathrm{r}}^{2+}$
    4. D.$\mathrm{C}{\mathrm{r}}^{2+}$ and $\mathrm{C}{\mathrm{o}}^{2+}$
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    Answer: C

16. Q852023 · 29 Jan 2023 · Shift 1· Numerical answer
    
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    Answer: 2

17. Q822023 · 29 Jan 2023 · Shift 2· Numerical answer

    The equilibrium constant for the reaction $\mathrm{Zn}(\mathrm{s})+\mathrm{S}{\mathrm{n}}^{2+}(\mathrm{aq})\rightleftharpoons \mathrm{Z}{\mathrm{n}}^{2+}(\mathrm{aq})+\mathrm{Sn}(\mathrm{s})$ is $1\times 10^{20}$ at $298\mathrm{K}$. The magnitude of standard electrode potential of $Sn/S{\mathrm{n}}^{2+}$ if ${\mathrm{E}}_{\mathrm{Z}{\mathrm{n}}^{2+}/Zn}^{\ominus }=-0.76\mathrm{V}$ is ____ $\times 10^{-2}\mathrm{V}$. (Nearest integer) Given : $\frac{2.303\mathrm{RT}}{\mathrm{F}}=0.059\mathrm{V}$

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    Answer: 17