Electrochemistry JEE Main PYQs (2020–2026)

Solved Electrochemistry PYQs

3 recent questions with answers. The full set of 160 is free to practise.

1. JEE Main 2026EasyGalvanic Cells, Cell Potential & Electrochemical Series
   Q1

   Given at 298 K :
   
   $$\begin{array}{rl}& E_{{Fe}^{2+}/Fe}^{\ominus }=X\text{ Volt }\\ & E_{{Fe}^{3+}/Fe}^{\ominus }=Y\text{ Volt }\end{array}$$
   
   The $E_{{Fe}^{3+}/{Fe}^{2+}}^{\ominus }$ in Volt at 298 K is given by :

   • A$2X-3Y$
   • B$3Y-2X$
   • C$3Y+2X$
   • D$Y+X$

   Show answer & solution

   Correct answer: (B)

   $${Fe}^{+2}(aq)+2e^{-}\to Fe(s)\dots \dots ..\Delta G_1^{\circ }$$
   
   $${Fe}^{+3}(aq)+3e^{-}\to Fe(s)\dots \dots ..\Delta G_2^{\circ }$$
   
   $${Fe}^{+3}(aq)+e^{-}\to {Fe}^{+2}(aq)\dots \dots ..\Delta G_3^{\circ }$$
   
   $$\begin{array}{rl}& \text{ iii }=\text{ ii }-i\\ -1\times F\times E_{\frac{{Fe}^{3+}}{{Fe}^{2+}}}^{\circ }& \\ =-3\times F\times y-(-2\times F\times x)& \\ & E_{{Fe}^{3+}/{Fe}^{2+}}^{\circ }=3y-2x\end{array}$$
   
   Option (B) is correct
2. JEE Main 2026MediumNernst Equation & Cell Potential Calculations
   Q2

   In the given electrochemical cell, $Ag(s)|AgCl(s)|{FeCl}_2(aq),{FeCl}_3(aq)\mid Pt(s)$ at 298 K , the cell potential ( $E_{\text{cell }}$ ) will increase when :
   
   A. Concentration of ${Fe}^{2+}$ is increased.
   
   B. Concentration of ${Fe}^{3+}$ is decreased.
   
   C. Concentration of ${Fe}^{2+}$ is decreased.
   
   D. Concentration of ${Fe}^{3+}$ is increased.
   
   E. Concentration of ${Cl}^{-}$ is increased.
   
   Choose the correct answer from the options given below :

   • AC, D and E Only
   • BA and B Only
   • CB Only
   • DA and E Only

   Show answer & solution

   Correct answer: (A)

   $$\begin{array}{rl}& {Cl}_{aq}^{-}+{Ag}_{S)}+{Fe}_{aq}^{+3}\to {Fe}_{aq}^{+2}+{AgCl}_{(S)}\\ & E_{cell}=E_{cell}^{\circ }-\frac{0.059}{1}\log \frac{\left[{Fe}^{2+}\right]}{\left[{Cl}^{-}\right]\left[{Fe}^{3+}\right]}\end{array}$$
3. JEE Main 2026MediumConductance, Specific Conductivity & Molar Conductivity
   Q3

   For strong electrolyte ${\Lambda }_m$ increases slowly with dilution and can be represented by the equation
   
   $${\Lambda }_m={\Lambda }_m^{\circ }-A{c}^{1/2}$$
   
   Molar conductivity values of the solutions of strong electrolyte AB at 18°C are given below :
   
   c [mol L-1]
   
   0.04
   
   0.09
   
   0.16
   
   0.25
   
   ${\Lambda }_m$ [S cm2 mol-1]
   
   96.1
   
   95.7
   
   95.3
   
   94.9
   
   The value of constant A based on the above data [in S cm2 mol-1/(mol/L)1/2] unit is ________.

   Numerical answer type

   Show answer & solution

   Correct answer: 4

   We use the given relation for a strong electrolyte:
   
   Using equation : ${\Lambda }_m={\Lambda }_m^0-A\sqrt{c}$
   
   Now substitute the first set of data: $c=0.04$ and ${\Lambda }_m=96.1$ .
   
   $$\begin{array}{rl}& 96.1={\Lambda }_m^0-A\sqrt{0.04}\\ & 96.1={\Lambda }_m^0-A\times 0.2...(i)\\ & 95.7={\Lambda }_m^0-A\times \sqrt{0.09}\\ & 95.7={\Lambda }_m^0-A\times 0.3...(ii)\end{array}$$
   
   Now subtract equation (ii) from equation (i) so that ${\Lambda }_m^0$ cancels out:
   
   From eq. (1) and eq. (2)
   
   $$\begin{array}{rl}(96.1-95.7)& =({\Lambda }_m^0-A\times 0.2)-({\Lambda }_m^0-A\times 0.3)\\ 0.4& =-0.2A+0.3A\\ 0.4& =0.1A\\ A& =4\end{array}$$

Topic-wise question count

Where JEE Main has asked from Electrochemistry, most frequent first.

• Nernst Equation & Cell Potential Calculations38
• Galvanic Cells, Cell Potential & Electrochemical Series29
• Electrolysis & Faraday's Laws of Electrolysis29
• Conductance, Specific Conductivity & Molar Conductivity28
• Relation between Free Energy (Delta G), Equilibrium Constant & E_cell14
• Commercial Batteries, Fuel Cells and Corrosion12
• Kohlrausch's Law and Its Applications10

Year-wise Electrochemistry questions in JEE Main

Number of questions from this chapter in each year's paper(s).