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CHXII03:ELECTROCHEMISTRY

329915 Assertion :
The cell potential of mercury cell is $1.35 V$ which remains constant
Reason :
In mercury cell, the electrolyte is a paste of $KOH$ and $ZnO$ .

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

In a mercury cell, represented by the reaction
$Zn (Hg) + HgO \to ZnO + Hg$
A unique characteristic is that the cell potential remains constant throughout its operational life. Because the overall redox reaction does not involve any ions in solution. The electrolyte is a paste of $KOH$ and $ZnO$ . So, option (2) is correct.

CHXII03:ELECTROCHEMISTRY

329916 A depolariser used in dry cell batteries is:

1 Sodium phosphate

2 Potassium hydroxide

3 Ammonium chloride

4 Manganese dioxide

Explanation:

$M n O_{2}$ is Leclanche cell.

CHXII03:ELECTROCHEMISTRY

329917 The reaction at cathode in the cells commonly used in clocks involves

1 reduction of Mn from +4 to +3

2 oxidation of Mn from +2 to +7

3 reduction of Mn from +7 to +2

4 oxidation of Mn from +3 to +4 .

Explanation:

Dry cell is commonly used in clocks. The reaction at cathode is given by
$\begin{array}{l} 2 M n O_{2 (s)} + 2 {N H}_{4 (a q)}^{+} + 2 e^{-} \to \\ M n_{2} O_{3 (s)} + 2 N H_{3 (g)} + H_{2} O \end{array}$
Thus, in the reaction, manganese $(Mn)$ is reduced from the +4 oxidation state to the +3 state. So, the correct option is (1).

JEE Main - 2024

CHXII03:ELECTROCHEMISTRY

329918 Mark the incorrect statement for a dry cell

1 Mn is reduced from +4 to +3 state

2

N H_{3}

gas is liberated out at anode

3 Zn is used as anode

4 A paste of

N H_{4} C l a n d Z n C l_{2}

is used to fill the space between electrodes.

Explanation:

$N H_{3}$ produced due to cathodic reaction,
$M n O_{2} {+ N H}_{4}^{+} + e \to M n O (O H) + N H_{3}$ combines with $Z n^{2 +} t o f o r m {[Z n {(N H_{3})}_{4}]}^{2 +}$ .

CHXII03:ELECTROCHEMISTRY

329930 Match the column I with column II and choose the the correct option.

Column I	Column II
A. Cell in which electrolyte is a paste of KOH and ZnO. This cell is used in low current devices like hearing aids, watches, etc.	P. $H_{2} - O_{2}$ fuel cell
B. Cell in which $38 %$ $H_{2} S O_{4}$ solution is used as an electrolyte	Q. Mercury cell
C. Cell in which vapours produced during electrochemical reaction were condensed and added to drinking water	R. Lead storage battery
D. Cell having longer life than lead storage cell and is expensive to manufacture	S. Nickel cadmium cell

1 A - R, B - Q, C - P, D - S

2 A - Q, B - R, C - P, D - S

3 A - S, B - R, C - Q, D - P

4 A - Q, B - R, C - S, D - P

CHXII03:ELECTROCHEMISTRY

329915 Assertion :
The cell potential of mercury cell is $1.35 V$ which remains constant
Reason :
In mercury cell, the electrolyte is a paste of $KOH$ and $ZnO$ .

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

In a mercury cell, represented by the reaction
$Zn (Hg) + HgO \to ZnO + Hg$
A unique characteristic is that the cell potential remains constant throughout its operational life. Because the overall redox reaction does not involve any ions in solution. The electrolyte is a paste of $KOH$ and $ZnO$ . So, option (2) is correct.

CHXII03:ELECTROCHEMISTRY

329916 A depolariser used in dry cell batteries is:

1 Sodium phosphate

2 Potassium hydroxide

3 Ammonium chloride

4 Manganese dioxide

Explanation:

$M n O_{2}$ is Leclanche cell.

CHXII03:ELECTROCHEMISTRY

329917 The reaction at cathode in the cells commonly used in clocks involves

1 reduction of Mn from +4 to +3

2 oxidation of Mn from +2 to +7

3 reduction of Mn from +7 to +2

4 oxidation of Mn from +3 to +4 .

Explanation:

Dry cell is commonly used in clocks. The reaction at cathode is given by
$\begin{array}{l} 2 M n O_{2 (s)} + 2 {N H}_{4 (a q)}^{+} + 2 e^{-} \to \\ M n_{2} O_{3 (s)} + 2 N H_{3 (g)} + H_{2} O \end{array}$
Thus, in the reaction, manganese $(Mn)$ is reduced from the +4 oxidation state to the +3 state. So, the correct option is (1).

JEE Main - 2024

CHXII03:ELECTROCHEMISTRY

329918 Mark the incorrect statement for a dry cell

1 Mn is reduced from +4 to +3 state

2

N H_{3}

gas is liberated out at anode

3 Zn is used as anode

4 A paste of

N H_{4} C l a n d Z n C l_{2}

is used to fill the space between electrodes.

Explanation:

$N H_{3}$ produced due to cathodic reaction,
$M n O_{2} {+ N H}_{4}^{+} + e \to M n O (O H) + N H_{3}$ combines with $Z n^{2 +} t o f o r m {[Z n {(N H_{3})}_{4}]}^{2 +}$ .

CHXII03:ELECTROCHEMISTRY

329930 Match the column I with column II and choose the the correct option.

Column I	Column II
A. Cell in which electrolyte is a paste of KOH and ZnO. This cell is used in low current devices like hearing aids, watches, etc.	P. $H_{2} - O_{2}$ fuel cell
B. Cell in which $38 %$ $H_{2} S O_{4}$ solution is used as an electrolyte	Q. Mercury cell
C. Cell in which vapours produced during electrochemical reaction were condensed and added to drinking water	R. Lead storage battery
D. Cell having longer life than lead storage cell and is expensive to manufacture	S. Nickel cadmium cell

1 A - R, B - Q, C - P, D - S

2 A - Q, B - R, C - P, D - S

3 A - S, B - R, C - Q, D - P

4 A - Q, B - R, C - S, D - P

CHXII03:ELECTROCHEMISTRY

329915 Assertion :
The cell potential of mercury cell is $1.35 V$ which remains constant
Reason :
In mercury cell, the electrolyte is a paste of $KOH$ and $ZnO$ .

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

In a mercury cell, represented by the reaction
$Zn (Hg) + HgO \to ZnO + Hg$
A unique characteristic is that the cell potential remains constant throughout its operational life. Because the overall redox reaction does not involve any ions in solution. The electrolyte is a paste of $KOH$ and $ZnO$ . So, option (2) is correct.

CHXII03:ELECTROCHEMISTRY

329916 A depolariser used in dry cell batteries is:

1 Sodium phosphate

2 Potassium hydroxide

3 Ammonium chloride

4 Manganese dioxide

Explanation:

$M n O_{2}$ is Leclanche cell.

CHXII03:ELECTROCHEMISTRY

329917 The reaction at cathode in the cells commonly used in clocks involves

1 reduction of Mn from +4 to +3

2 oxidation of Mn from +2 to +7

3 reduction of Mn from +7 to +2

4 oxidation of Mn from +3 to +4 .

Explanation:

Dry cell is commonly used in clocks. The reaction at cathode is given by
$\begin{array}{l} 2 M n O_{2 (s)} + 2 {N H}_{4 (a q)}^{+} + 2 e^{-} \to \\ M n_{2} O_{3 (s)} + 2 N H_{3 (g)} + H_{2} O \end{array}$
Thus, in the reaction, manganese $(Mn)$ is reduced from the +4 oxidation state to the +3 state. So, the correct option is (1).

JEE Main - 2024

CHXII03:ELECTROCHEMISTRY

329918 Mark the incorrect statement for a dry cell

1 Mn is reduced from +4 to +3 state

2

N H_{3}

gas is liberated out at anode

3 Zn is used as anode

4 A paste of

N H_{4} C l a n d Z n C l_{2}

is used to fill the space between electrodes.

Explanation:

$N H_{3}$ produced due to cathodic reaction,
$M n O_{2} {+ N H}_{4}^{+} + e \to M n O (O H) + N H_{3}$ combines with $Z n^{2 +} t o f o r m {[Z n {(N H_{3})}_{4}]}^{2 +}$ .

CHXII03:ELECTROCHEMISTRY

329930 Match the column I with column II and choose the the correct option.

Column I	Column II
A. Cell in which electrolyte is a paste of KOH and ZnO. This cell is used in low current devices like hearing aids, watches, etc.	P. $H_{2} - O_{2}$ fuel cell
B. Cell in which $38 %$ $H_{2} S O_{4}$ solution is used as an electrolyte	Q. Mercury cell
C. Cell in which vapours produced during electrochemical reaction were condensed and added to drinking water	R. Lead storage battery
D. Cell having longer life than lead storage cell and is expensive to manufacture	S. Nickel cadmium cell

1 A - R, B - Q, C - P, D - S

2 A - Q, B - R, C - P, D - S

3 A - S, B - R, C - Q, D - P

4 A - Q, B - R, C - S, D - P

CHXII03:ELECTROCHEMISTRY

329915 Assertion :
The cell potential of mercury cell is $1.35 V$ which remains constant
Reason :
In mercury cell, the electrolyte is a paste of $KOH$ and $ZnO$ .

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

In a mercury cell, represented by the reaction
$Zn (Hg) + HgO \to ZnO + Hg$
A unique characteristic is that the cell potential remains constant throughout its operational life. Because the overall redox reaction does not involve any ions in solution. The electrolyte is a paste of $KOH$ and $ZnO$ . So, option (2) is correct.

CHXII03:ELECTROCHEMISTRY

329916 A depolariser used in dry cell batteries is:

1 Sodium phosphate

2 Potassium hydroxide

3 Ammonium chloride

4 Manganese dioxide

Explanation:

$M n O_{2}$ is Leclanche cell.

CHXII03:ELECTROCHEMISTRY

329917 The reaction at cathode in the cells commonly used in clocks involves

1 reduction of Mn from +4 to +3

2 oxidation of Mn from +2 to +7

3 reduction of Mn from +7 to +2

4 oxidation of Mn from +3 to +4 .

Explanation:

Dry cell is commonly used in clocks. The reaction at cathode is given by
$\begin{array}{l} 2 M n O_{2 (s)} + 2 {N H}_{4 (a q)}^{+} + 2 e^{-} \to \\ M n_{2} O_{3 (s)} + 2 N H_{3 (g)} + H_{2} O \end{array}$
Thus, in the reaction, manganese $(Mn)$ is reduced from the +4 oxidation state to the +3 state. So, the correct option is (1).

JEE Main - 2024

CHXII03:ELECTROCHEMISTRY

329918 Mark the incorrect statement for a dry cell

1 Mn is reduced from +4 to +3 state

2

N H_{3}

gas is liberated out at anode

3 Zn is used as anode

4 A paste of

N H_{4} C l a n d Z n C l_{2}

is used to fill the space between electrodes.

Explanation:

$N H_{3}$ produced due to cathodic reaction,
$M n O_{2} {+ N H}_{4}^{+} + e \to M n O (O H) + N H_{3}$ combines with $Z n^{2 +} t o f o r m {[Z n {(N H_{3})}_{4}]}^{2 +}$ .

CHXII03:ELECTROCHEMISTRY

329930 Match the column I with column II and choose the the correct option.

Column I	Column II
A. Cell in which electrolyte is a paste of KOH and ZnO. This cell is used in low current devices like hearing aids, watches, etc.	P. $H_{2} - O_{2}$ fuel cell
B. Cell in which $38 %$ $H_{2} S O_{4}$ solution is used as an electrolyte	Q. Mercury cell
C. Cell in which vapours produced during electrochemical reaction were condensed and added to drinking water	R. Lead storage battery
D. Cell having longer life than lead storage cell and is expensive to manufacture	S. Nickel cadmium cell

1 A - R, B - Q, C - P, D - S

2 A - Q, B - R, C - P, D - S

3 A - S, B - R, C - Q, D - P

4 A - Q, B - R, C - S, D - P

CHXII03:ELECTROCHEMISTRY

329915 Assertion :
The cell potential of mercury cell is $1.35 V$ which remains constant
Reason :
In mercury cell, the electrolyte is a paste of $KOH$ and $ZnO$ .

1 Both Assertion and Reason are correct and Reason is the correct explanation of the Assertion.

2 Both Assertion and Reason are correct but Reason is not the correct explanation of the Assertion.

3 Assertion is correct but Reason is incorrect.

4 Assertion is incorrect but Reason is correct.

Explanation:

In a mercury cell, represented by the reaction
$Zn (Hg) + HgO \to ZnO + Hg$
A unique characteristic is that the cell potential remains constant throughout its operational life. Because the overall redox reaction does not involve any ions in solution. The electrolyte is a paste of $KOH$ and $ZnO$ . So, option (2) is correct.

CHXII03:ELECTROCHEMISTRY

329916 A depolariser used in dry cell batteries is:

1 Sodium phosphate

2 Potassium hydroxide

3 Ammonium chloride

4 Manganese dioxide

Explanation:

$M n O_{2}$ is Leclanche cell.

CHXII03:ELECTROCHEMISTRY

329917 The reaction at cathode in the cells commonly used in clocks involves

1 reduction of Mn from +4 to +3

2 oxidation of Mn from +2 to +7

3 reduction of Mn from +7 to +2

4 oxidation of Mn from +3 to +4 .

Explanation:

Dry cell is commonly used in clocks. The reaction at cathode is given by
$\begin{array}{l} 2 M n O_{2 (s)} + 2 {N H}_{4 (a q)}^{+} + 2 e^{-} \to \\ M n_{2} O_{3 (s)} + 2 N H_{3 (g)} + H_{2} O \end{array}$
Thus, in the reaction, manganese $(Mn)$ is reduced from the +4 oxidation state to the +3 state. So, the correct option is (1).

JEE Main - 2024

CHXII03:ELECTROCHEMISTRY

329918 Mark the incorrect statement for a dry cell

1 Mn is reduced from +4 to +3 state

2

N H_{3}

gas is liberated out at anode

3 Zn is used as anode

4 A paste of

N H_{4} C l a n d Z n C l_{2}

is used to fill the space between electrodes.

Explanation:

$N H_{3}$ produced due to cathodic reaction,
$M n O_{2} {+ N H}_{4}^{+} + e \to M n O (O H) + N H_{3}$ combines with $Z n^{2 +} t o f o r m {[Z n {(N H_{3})}_{4}]}^{2 +}$ .

CHXII03:ELECTROCHEMISTRY

329930 Match the column I with column II and choose the the correct option.

Column I	Column II
A. Cell in which electrolyte is a paste of KOH and ZnO. This cell is used in low current devices like hearing aids, watches, etc.	P. $H_{2} - O_{2}$ fuel cell
B. Cell in which $38 %$ $H_{2} S O_{4}$ solution is used as an electrolyte	Q. Mercury cell
C. Cell in which vapours produced during electrochemical reaction were condensed and added to drinking water	R. Lead storage battery
D. Cell having longer life than lead storage cell and is expensive to manufacture	S. Nickel cadmium cell

1 A - R, B - Q, C - P, D - S

2 A - Q, B - R, C - P, D - S

3 A - S, B - R, C - Q, D - P

4 A - Q, B - R, C - S, D - P