MCQ 81: Primary vs. Secondary Cells
Question: Which of the following is a characteristic of secondary cells?
A) They cannot be recharged.
B) They have a fixed voltage.
C) They can undergo multiple charge-discharge cycles.
D) They are always smaller than primary cells.
Answer: C) They can undergo multiple charge-discharge cycles.
Explanation: Secondary cells, or rechargeable batteries, can be cycled multiple times, allowing for repeated charging and discharging.
MCQ 82: Oxidation Numbers
Question: In a redox reaction, the change in oxidation number of an element indicates:
A) The total mass change of the reaction.
B) The loss or gain of electrons.
C) The concentration of reactants.
D) The energy change of the reaction.
Answer: B) The loss or gain of electrons.
Explanation: Changes in oxidation numbers reflect the transfer of electrons during redox reactions, with increases indicating oxidation and decreases indicating reduction.
MCQ 83: Ionic Mobility
Question: Which ion generally has the highest mobility in solution?
A) Na⁺
B) Cl⁻
C) K⁺
D) Ca²⁺
Answer: A) Na⁺
Explanation: Sodium ions (Na⁺) typically exhibit higher mobility in aqueous solutions compared to other common ions, facilitating faster conduction.
MCQ 84: Electrode Reactions in Batteries
Question: In a lithium-ion battery, lithium ions move from:
A) Anode to cathode during discharge
B) Cathode to anode during discharge
C) Anode to cathode during charging
D) Cathode to anode during charging
Answer: A) Anode to cathode during discharge
Explanation: During discharge, lithium ions move from the anode to the cathode, where they participate in the electrochemical reaction that generates electricity.
MCQ 85: Cell Potential Calculation
Question: In the Nernst equation, what does the term RTnFnFRT represent?
A) Temperature correction factor
B) Standard cell potential
C) Change in Gibbs free energy
D) Concentration of ions
Answer: A) Temperature correction factor
Explanation: The term RTnFnFRT in the Nernst equation adjusts the cell potential based on temperature, where R is the gas constant, T is the temperature in Kelvin, n is the number of moles of electrons, and F is Faraday’s constant.
MCQ 86: Role of a Salt Bridge
Question: The primary function of a salt bridge in an electrochemical cell is to:
A) Facilitate electron flow.
B) Maintain electrical neutrality.
C) Increase the concentration of ions.
D) Isolate the electrodes.
Answer: B) Maintain electrical neutrality.
Explanation: The salt bridge allows ions to migrate between the two half-cells, maintaining charge balance and preventing the buildup of charge that would stop the reaction.
MCQ 87: Electrochemical Cell Reactions
Question: In a Daniell cell, which metal acts as the anode?
A) Copper
B) Zinc
C) Silver
D) Gold
Answer: B) Zinc
Explanation: In a Daniell cell, zinc serves as the anode, where it undergoes oxidation, while copper acts as the cathode where reduction occurs.
MCQ 88: Conductance Measurement
Question: What unit is commonly used to express conductivity?
A) Ohm
B) Siemens
C) Volt
D) Coulomb
Answer: B) Siemens
Explanation: Conductivity is measured in siemens (S), which quantifies how well a solution conducts electricity.
MCQ 89: Reaction Quotient (Q)
Question: When calculating the reaction quotient (Q), which of the following is considered?
A) Concentrations of only reactants
B) Concentrations of only products
C) Concentrations of both reactants and products
D) Temperature of the solution only
Answer: C) Concentrations of both reactants and products
Explanation: The reaction quotient (Q) is calculated using the concentrations of both reactants and products at any point during the reaction.
MCQ 90: Electrolysis Products
Question: During the electrolysis of water, what gases are produced at the electrodes?
A) Nitrogen and oxygen
B) Hydrogen and chlorine
C) Hydrogen and oxygen
D) Carbon dioxide and hydrogen
Answer: C) Hydrogen and oxygen
Explanation: Electrolysis of water produces hydrogen gas at the cathode and oxygen gas at the anode.
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