MCQ 31: Electron Flow in Cells
Question: What drives the flow of electrons in an electrochemical cell?
A) Chemical potential difference
B) Thermal energy
C) Magnetic fields
D) Electric field
Answer: A) Chemical potential difference
Explanation: The flow of electrons in an electrochemical cell is driven by the difference in chemical potential between the anode and cathode.
MCQ 32: Electrochemical Reactions
Question: In the reaction Zn + Cu²⁺ → Zn²⁺ + Cu, which species is oxidized?
A) Zn
B) Cu²⁺
C) Zn²⁺
D) Cu
Answer: A) Zn
Explanation: In this reaction, zinc (Zn) loses electrons and is oxidized to zinc ions (Zn²⁺), while copper ions (Cu²⁺) are reduced to solid copper (Cu).
MCQ 33: Relation of Nernst Equation to Equilibrium
Question: The Nernst equation can be used to determine the cell potential at equilibrium. What is the value of E at equilibrium?
A) Positive
B) Negative
C) Zero
D) Undefined
Answer: C) Zero
Explanation: At equilibrium, the cell potential (E) is zero because there is no net change in concentrations of reactants and products.
MCQ 34: Faraday’s Constant
Question: What is the approximate value of Faraday’s constant (F)?
A) 1.6 × 10⁻¹⁹ C/mol
B) 96,485 C/mol
C) 6.022 × 10²³ C/mol
D) 964.85 C/mol
Answer: B) 96,485 C/mol
Explanation: Faraday’s constant (F) is approximately 96,485 coulombs per mole of electrons, representing the charge of one mole of elementary charge carriers.
MCQ 35: Concentration Cells
Question: In a concentration cell, the cell potential arises from:
A) Differences in electrode material
B) Differences in temperature
C) Differences in ion concentration
D) Differences in pressure
Answer: C) Differences in ion concentration
Explanation: The cell potential in a concentration cell is generated due to the difference in concentrations of the same ion on either side of the cell.
MCQ 36: Cell Potential Calculation
Question: Which of the following does NOT affect the cell potential of a galvanic cell?
A) Concentration of the reactants and products
B) Temperature of the system
C) The physical shape of the cell
D) The nature of the electrodes
Answer: C) The physical shape of the cell
Explanation: The physical shape of the galvanic cell does not influence the cell potential; instead, factors like concentration, temperature, and electrode materials do.
MCQ 37: Electrochemical Corrosion
Question: Which of the following is an example of an electrochemical corrosion process?
A) Rusting of iron
B) Oxidation of magnesium
C) Sulfide formation
D) Ion exchange
Answer: A) Rusting of iron
Explanation: Rusting of iron is an electrochemical process where iron oxidizes in the presence of moisture and oxygen, forming iron oxides (rust).
MCQ 38: Polarization in Electrochemical Cells
Question: What is polarization in the context of electrochemical cells?
A) The alignment of dipoles in the electrolyte
B) A reduction in cell potential due to buildup of products
C) An increase in temperature during operation
D) The movement of ions toward the electrodes
Answer: B) A reduction in cell potential due to buildup of products
Explanation: Polarization refers to the decrease in cell potential caused by the accumulation of reaction products at the electrodes, hindering further reaction.
MCQ 39: Standard Hydrogen Electrode (SHE)
Question: What is the purpose of the Standard Hydrogen Electrode (SHE)?
A) It serves as a reference for measuring electrode potentials.
B) It is used to generate electricity.
C) It acts as a strong oxidizing agent.
D) It is a common electrode in galvanic cells.
Answer: A) It serves as a reference for measuring electrode potentials.
Explanation: The Standard Hydrogen Electrode is used as a reference point for measuring and comparing the standard electrode potentials of other half-cells.
MCQ 40: Salt Bridge Function
Question: What is the primary function of a salt bridge in an electrochemical cell?
A) To provide a source of ions
B) To complete the electrical circuit
C) To maintain neutral charge in each half-cell
D) To separate the two half-cells
Answer: C) To maintain neutral charge in each half-cell
Explanation: The salt bridge allows the flow of ions between the half-cells, maintaining charge neutrality by compensating for the movement of electrons through the external circuit.
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