jee main chemistry important questions | Electrochemistry jee main questions FREE

Q 1 :

40 mL of a mixture of ${CH}_{3} COOH$ and HCl (aqueous solution) is titrated against 0.1 M NaOH solution conductometrically. Which of the following statement is correct?
[2025]

The concentration of ${CH}_{3} COOH$ in the original mixture is 0.005 M.
The concentration of HCl in the original mixture is 0.005 M.
${CH}_{3} COOH$ is neutralised first followed by neutralisation of HCl.
Point ‘C’ indicates the complete neutralisation of HCl.

1

2

3

4

(2)

First NaOH reacts with HCl. Point B indicates complete neutralization of HCl. 2 mL of NaOH is used to neutralize HCl.

When NaOH completely neutralizes HCl:

$mmol of NaOH = mmol of HCl$

$M_{NaOH} \times V_{NaOH} (that reacts with HCl) = M_{HCl} \times V_{HCl}$

$0.1 \times 2 = M_{HCl} \times 40$

$M_{HCl} = 0.005 M$

When HCl is completely neutralized, then NaOH reacts with ${CH}_{3} COOH$ . Thus, (5−2) mL = 3 mL of NaOH reacts with ${CH}_{3} COOH$ . Point C indicates complete neutralization of ${CH}_{3} COOH$ .

When NaOH completely neutralizes ${CH}_{3} COOH$ :

$mmol of NaOH = {mmol of CH}_{3} COOH$

$M_{N a O H} \times V_{N a O H}$ (that reacts with ${CH}_{3} COOH$ )

$= M_{C H_{3} C O O H} \times V_{C H_{3} C O O H}$

$0.1 \times 3$ $= M_{C H_{3} C O O H} \times 40$

$M_{C H_{3} C O O H} = 0.0075 M$

Q 2 :

Given below are two statements: [2025]

Statement I: Corrosion is an electrochemical phenomenon in which pure metal acts as an anode and impure metal as a cathode.

Statement II: The rate of corrosion is more in alkaline medium than in acidic medium.

In the light of the above statements, choose the correct answer from the options given below:

Both Statement I and Statement II are false
Both Statement I and Statement II are true
Statement I is true but Statement II is false
Statement I is false but Statement II is true

1

2

3

4

(3)

Rate of corrosion is generally more in acidic medium.

Q 3 :

For a closed circuit Daniell cell, which of the following plots is the accurate one at a given temperature? [2026]

1

2

3

4

(2)

$E_{cell}^{\circ} remain constant with time.$

Q 4 :

MX is a sparingly soluble salt that follows the given solubility equilibrium at 298 K.

$M X (s) ⇌ M^{+} (a q) + X^{-} (a q); K_{s p} = 10^{- 10}$

If the standard reduction potential for $M^{+} (a q) \overset{+ e^{-}}{\to} M (s)$ is $(E_{M^{+} / M}^{⊝}) = 0.79 V,$ then the value of the standard reduction potential for the metal/metal insoluble salt electrode $E_{X^{-} / M X (s) / M}^{⊝}$ is ___________________mV. (nearest integer).

$[Given: \frac{2.303 R T}{F} = 0.059 V]$ [2026]

(200)

$E_{X^{-} / M X (s) / M}^{\circ} = E_{M^{+} / M}^{\circ} + \frac{0.0591}{n} \log K_{s p}$

$= 0.79 + \frac{0.059}{1} \log (10^{- 10})$

$= 0.79 - 0.59$

$= 0.20 V = 200 mV$

Q 5 :

Consider the following electrochemical cell :

$P t | O_{2} (g) (1 b a r) | H C l (a q) ‖ M^{2 +} (a q, 1.0 M) | M (s)$

The pH above which, oxygen gas would start to evolve at anode is ________ (nearest integer).

[2026]

(4)

$For spontaneity E_{cell} > 0$

$At limiting condition :$

$E_{oxi} (anode) = - E_{red} (cathode)$

$H_{2} O \to 2 H^{+} + \frac{1}{2} O_{2} + 2 e^{-}$

$E = E ° - \frac{0.059}{2} \log [\frac{{[H^{+}]}^{2} \times P_{O_{2}}^{1 / 2}}{1}]$

$- 0.997 = - 1.23 + 0.059 \times pH$

$pH = 3.94$

$pH \approx 4$

Q 6 :

Concentration of $K^{+}$ ions inside a biological cell was found to be 25 times higher than that outside. The magnitude of the potential difference between the two sides of the cell in close to _____ mV (nearest integer) ( $2.303 \frac{R T}{F} = 59 mV, \log 5 = 0.7$ ) (difference in concentration of other ions can be taken as negligible).

(83)

Q 7 :

In a saturated solution of $A g B r (K_{s p} = 2 \times 10^{- 13})$ , if $10^{- 7}$ moles of $A g N O_{3}$ are added to 1 litre of this solution, find specific conductance of this solution in terms of $10^{- 7} S m^{- 1}$ units.

Given: $λ_{(A g^{+})}^{\circ} = 6 \times 10^{- 3} S m^{2} / m o l$

$λ_{(N O_{3}^{-})}^{\circ} = 7 \times 10^{- 3} S m^{2} / m o l$

$λ_{(B r^{-})}^{\circ} = 8 \times 10^{- 3} S m^{2} / m o l$

(69)

$A g B r_{(s)} ⇌ \underset{(s + 10^{- 7})}{A g^{+}} + \underset{s}{B r^{-}}$

$s^{2} + 10^{- 7} s - 20 \times 10^{- 14} = 0$

$s = \frac{- 10^{- 7} + \sqrt{10^{- 14} + 80 \times 10^{- 14}}}{2} = 4 \times 10^{- 7}$

$[A g^{+}] = 5 \times 10^{- 7} M$

$[B r^{-}] = 4 \times 10^{- 7} M$

$[N O_{3}^{-}] = 1 \times 10^{- 7} M$

$Λ ° = \frac{K}{1000 C}$ $\Rightarrow K_{A g^{+}}^{1} = 6 \times 10^{- 3} \times 1000 \times 5 \times 10^{- 7}$

$= 30 \times 10^{- 7} s^{- 1} m^{2} / m o l$

$K_{N O_{3}^{-}}^{1} = 7 \times 1 \times 10^{- 7} s m^{2} / m o l$

$K_{B r^{-}}^{1} = 8 \times 4 \times 10^{- 7} s m^{2} / m o l = 32 \times 10^{- 7}$

$K_{total}^{1} = 69 \times 10^{- 7} s m^{2} / m o l$

Q 8 :

Given below are two statements:

Statement I: The limiting molar conductivity of KCl (strong electrolyte) is higher compared to that of ${CH}_{3} COOH$ (weak electrolyte).

Statement II: Molar conductivity increases with decrease in concentration of electrolyte.

In the light of the above statements, choose the most appropriate answer from the options given below:

Statement I is true but Statement II is false.
Statement I is false but Statement II is true.
Both Statement I and Statement II are true.
Both Statement I and Statement II are false.

1

2

3

4

(2)

$Ion$	$H^{+}$	$K^{+}$	${Cl}^{-}$	${CH}_{3} {COO}^{-}$
$Λ_{m}^{\infty} (S {cm}^{2} {mol}^{- 1})$	$349.8$	$73.5$	$76.3$	$40.9$

So, $Λ_{m}^{\infty} ({CH}_{3} COOH) = Λ_{m}^{\infty} (H^{+}) + Λ_{m}^{\infty} ({CH}_{3} {COO}^{-}) = 349.8 + 40.9 = 390.7 S {cm}^{2} {mol}^{- 1}$

$Λ_{m}^{\infty} (KCl) = Λ_{m}^{\infty} (K^{+}) + Λ_{m}^{\infty} ({Cl}^{-}) = 73.5 + 76.3 = 149.8 S {cm}^{2} / mole$

$So statement-I is wrong or false.$

As the concentration decreases, the dilution increases, which increases the degree of dissociation, thus increasing the number of ions, which increases the molar conductance.

[IMAGE 48]

Q 9 :

The specific conductance of a saturated solution of silver bromide is $k {Scm}^{- 1}$ . The limiting ionic conductivity of ${Ag}^{+}$ and ${Br}^{-}$ ions are $x$ and $y$ , respectively. The solubility of silver bromide in ${gL}^{- 1}$ is:

(molar mass of AgBr = 188)

$\frac{k \times 1000}{x - y}$
$\frac{k}{x + y} \times 188$
$\frac{k \times 1000 \times 188}{x + y}$
$\frac{x + y}{k} \times \frac{1000}{188}$

1

2

3

4

(3)

$Λ_{m} = \frac{k}{M} \times 1000 \cdot (x + y) = \frac{k}{M} \times 1000$

$\Rightarrow M = \frac{1000 \times k}{x + y}$

$Solubility ({in g L}^{- 1}) = \frac{k \times 1000 \times 188}{x + y}$

Topic Question Set

Q 1 :

40 mL of a mixture of ${CH}_{3} COOH$ and HCl (aqueous solution) is titrated against 0.1 M NaOH solution conductometrically. Which of the following statement is correct?
[2025]

Q 3 :

For a closed circuit Daniell cell, which of the following plots is the accurate one at a given temperature? [2026]

Q 5 :

Consider the following electrochemical cell :

$P t | O_{2} (g) (1 b a r) | H C l (a q) ‖ M^{2 +} (a q, 1.0 M) | M (s)$

The pH above which, oxygen gas would start to evolve at anode is ________ (nearest integer).

[2026]

Q 9 :

The specific conductance of a saturated solution of silver bromide is $k {Scm}^{- 1}$ . The limiting ionic conductivity of ${Ag}^{+}$ and ${Br}^{-}$ ions are $x$ and $y$ , respectively. The solubility of silver bromide in ${gL}^{- 1}$ is:

(molar mass of AgBr = 188)

Want Us to Email you About Special Offers & Updates?

Topic Question Set

Q 1 : 40 mL of a mixture of CH3COOH and HCl (aqueous solution) is titrated against 0.1 M NaOH solution conductometrically. Which of the following statement is correct? [2025]

Q 3 : For a closed circuit Daniell cell, which of the following plots is the accurate one at a given temperature? [2026]

Q 5 : Consider the following electrochemical cell : Pt|O2(g) (1 bar)|HCl(aq)‖M2+(aq,1.0M)|M(s) The pH above which, oxygen gas would start to evolve at anode is ________ (nearest integer). [2026]

Q 7 : In a saturated solution of AgBr(Ksp=2×10-13), if 10-7 moles of AgNO3 are added to 1 litre of this solution, find specific conductance of this solution in terms of 10-7 S m-1 units. Given: λ(Ag+)∘=6×10-3 S m2/mol λ(NO3-)∘=7×10-3 S m2/mol λ(Br-)∘=8×10-3 S m2/mol

Q 9 : The specific conductance of a saturated solution of silver bromide is k Scm-1. The limiting ionic conductivity of Ag+ and Br- ions are x and y, respectively. The solubility of silver bromide in gL-1 is: (molar mass of AgBr = 188)

Want Us to Email you About Special Offers & Updates?

Q 1 :

40 mL of a mixture of ${CH}_{3} COOH$ and HCl (aqueous solution) is titrated against 0.1 M NaOH solution conductometrically. Which of the following statement is correct?
[2025]

Q 3 :

For a closed circuit Daniell cell, which of the following plots is the accurate one at a given temperature? [2026]

Q 5 :

Consider the following electrochemical cell :

$P t | O_{2} (g) (1 b a r) | H C l (a q) ‖ M^{2 +} (a q, 1.0 M) | M (s)$

The pH above which, oxygen gas would start to evolve at anode is ________ (nearest integer).

[2026]

Q 9 :

The specific conductance of a saturated solution of silver bromide is $k {Scm}^{- 1}$ . The limiting ionic conductivity of ${Ag}^{+}$ and ${Br}^{-}$ ions are $x$ and $y$ , respectively. The solubility of silver bromide in ${gL}^{- 1}$ is:

(molar mass of AgBr = 188)