MCQ 41: Role of Solvents
Question: In an electrochemical cell, what role do solvents play?
A) They provide ions for the reaction.
B) They act as a barrier between electrodes.
C) They alter the standard electrode potential.
D) They increase the cell temperature.
Answer: A) They provide ions for the reaction.
Explanation: Solvents, particularly aqueous solutions, provide ions that facilitate the conduction of electricity and participate in the electrochemical reactions.
MCQ 42: Electrode Reactions
Question: In the reaction 2Ag⁺ + Zn → 2Ag + Zn²⁺, what is being reduced?
A) Ag⁺
B) Zn
C) Zn²⁺
D) None of the above
Answer: A) Ag⁺
Explanation: In this reaction, silver ions (Ag⁺) gain electrons to form solid silver (Ag), indicating that Ag⁺ is being reduced.
MCQ 43: Cell Efficiency
Question: What is the maximum efficiency of an electrochemical cell?
A) 50%
B) 75%
C) 100%
D) It varies based on the cell design
Answer: C) 100%
Explanation: Theoretically, an electrochemical cell can be 100% efficient in converting chemical energy into electrical energy. However, practical cells often have lower efficiencies due to losses like polarization and resistance.
MCQ 44: Electrode Potential Calculations
Question: The standard electrode potential (E°) of a half-reaction is determined by:
A) The concentration of products only
B) The concentration of reactants only
C) The concentrations of both reactants and products
D) The temperature of the system only
Answer: C) The concentrations of both reactants and products
Explanation: The standard electrode potential (E°) is affected by the concentrations of both reactants and products in the electrochemical reaction, as described by the Nernst equation.
MCQ 45: Conductivity in Different Solutions
Question: Which of the following solutions would likely have the lowest conductivity?
A) 0.1 M NaCl
B) 0.1 M HCl
C) 0.1 M CH₃COOH
D) 0.1 M KBr
Answer: C) 0.1 M CH₃COOH
Explanation: Acetic acid (CH₃COOH) is a weak electrolyte and only partially dissociates in solution, leading to lower conductivity compared to the strong electrolytes NaCl, HCl, and KBr.
MCQ 46: Nernst Equation Constants
Question: In the Nernst equation, what do the variables R, T, n, and F represent?
A) R = gas constant, T = temperature, n = moles of electrons, F = Faraday’s constant
B) R = resistance, T = temperature, n = number of ions, F = Faraday’s constant
C) R = rate of reaction, T = time, n = number of electrons, F = force
D) R = resistivity, T = temperature, n = number of moles, F = Faraday’s number
Answer: A) R = gas constant, T = temperature, n = moles of electrons, F = Faraday’s constant
Explanation: In the Nernst equation, R is the universal gas constant, T is the absolute temperature in Kelvin, n is the number of moles of electrons transferred in the reaction, and F is Faraday’s constant.
MCQ 47: Electrochemical Cells and Batteries
Question: Which of the following is a primary difference between primary and secondary batteries?
A) Primary batteries can be recharged; secondary cannot.
B) Secondary batteries can be recharged; primary cannot.
C) Primary batteries have a higher energy density than secondary.
D) Secondary batteries are always larger than primary batteries.
Answer: B) Secondary batteries can be recharged; primary cannot.
Explanation: Primary batteries are designed for single-use and cannot be recharged, while secondary batteries can be recharged and reused multiple times.
MCQ 48: Reversible vs. Irreversible Cells
Question: A reversible electrochemical cell is characterized by:
A) Spontaneous reactions only
B) The ability to return to initial conditions
C) Higher efficiency than irreversible cells
D) All of the above
Answer: D) All of the above
Explanation: Reversible electrochemical cells can operate in both directions, allowing them to return to their initial conditions, and typically have higher efficiencies than irreversible cells.
MCQ 49: Ion Migration
Question: In an electrolytic cell, anions migrate toward the:
A) Anode
B) Cathode
C) Salt bridge
D) Electrolyte
Answer: A) Anode
Explanation: In an electrolytic cell, negatively charged ions (anions) migrate toward the anode, where oxidation occurs.
MCQ 50: Cell Potential Significance
Question: The sign of the cell potential (E) indicates:
A) The direction of electron flow
B) The temperature of the cell
C) The concentration of ions
D) The type of reaction occurring
Answer: A) The direction of electron flow
Explanation: The sign of the cell potential indicates whether the reaction is spontaneous (positive E) or non-spontaneous (negative E) and thus the direction of electron flow.
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