Dry Cell and Lead Accumulator NEET Questions

Physical Chemistry - Redox Reactions and Electrochemistry

Dry Cell and Lead Accumulator MCQ Questions


7.
What is the role of MnO₂ in a dry cell?
A.
It serves as the electrolyte
B.
It is a catalyst that does not get consumed
C.
It acts as the oxidising agent (gets reduced at the cathode)
D.
It acts as the reducing agent
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ANSWER :
C. It acts as the oxidising agent (gets reduced at the cathode)
8.
What is the EMF (voltage) of a typical fresh dry cell?
A.
Approximately 1.5 V
B.
Approximately 0.5 V
C.
Approximately 6.0 V
D.
Approximately 2.0 V
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ANSWER :
A. Approximately 1.5 V
9.
The role of ZnCl₂ in the dry cell paste is mainly to:
A.
Generate electrons at the anode
B.
React with the NH₃ gas formed at the cathode to prevent pressure build-up
C.
Increase the EMF of the cell
D.
Act as a catalyst for cathodic reduction
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ANSWER :
B. React with the NH₃ gas formed at the cathode to prevent pressure build-up
10.
Which of the following is NOT true about the dry cell?
A.
Zinc acts as the anode and is consumed during use
B.
Its EMF gradually falls as it discharges
C.
It is rechargeable and can be regenerated by passing current in the reverse direction
D.
The graphite rod serves only as a current collector and is not consumed
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ANSWER :
C. It is rechargeable and can be regenerated by passing current in the reverse direction
11.
Why does the EMF of a dry cell decrease over time even when not in use?
A.
The Zn container slowly reacts with NH₄Cl in the paste (self-discharge)
B.
The temperature of the cell falls
C.
The graphite rod oxidises in air
D.
MnO₂ slowly evaporates from the cell
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ANSWER :
A. The Zn container slowly reacts with NH₄Cl in the paste (self-discharge)
12.
The overall cell reaction in a Leclanché dry cell during discharge can be approximated as:
A.
2H₂ + O₂ → 2H₂O
B.
Zn + 2MnO₂ + 2NH₄⁺ → Zn²⁺ + Mn₂O₃ + 2NH₃ + H₂O
C.
Pb + PbO₂ + 2H₂SO₄ → 2PbSO₄ + 2H₂O
D.
Zn + 2H⁺ → Zn²⁺ + H₂
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ANSWER :
B. Zn + 2MnO₂ + 2NH₄⁺ → Zn²⁺ + Mn₂O₃ + 2NH₃ + H₂O