MCQ 11: Conductivity
Question: Which type of solution typically exhibits the highest conductivity?
A) Pure water
B) Distilled water
C) Saltwater
D) Sugar solution
Answer: C) Saltwater
Explanation: Saltwater contains dissolved ions (Na⁺, Cl⁻), which significantly increase its conductivity compared to pure or distilled water, which has very few ions.
MCQ 12: Electrochemical Series
Question: The electrochemical series is useful for determining which of the following?
A) The rate of a reaction
B) The spontaneity of a reaction
C) The pH of a solution
D) The temperature of a cell
Answer: B) The spontaneity of a reaction
Explanation: The electrochemical series ranks standard electrode potentials, which helps predict the spontaneity of redox reactions based on the relative strengths of oxidizing and reducing agents.
MCQ 13: Cell Reactions
Question: In a galvanic cell, what happens at the anode?
A) Oxidation occurs
B) Reduction occurs
C) Electrons are consumed
D) The cell potential increases
Answer: A) Oxidation occurs
Explanation: At the anode of a galvanic cell, oxidation occurs, meaning that the anode loses electrons, which flow to the cathode where reduction takes place.
MCQ 14: Nernst Equation Variables
Question: In the Nernst equation, which variable represents the reaction quotient?
A) E
B) E°
C) Q
D) n
Answer: C) Q
Explanation: In the Nernst equation, Q represents the reaction quotient, which is a measure of the relative concentrations of products and reactants at any given moment.
MCQ 15: Faraday’s Law
Question: According to Faraday’s first law of electrolysis, the mass of substance deposited at an electrode is directly proportional to:
A) The charge passed through the electrolyte
B) The voltage applied
C) The type of electrode used
D) The temperature of the solution
Answer: A) The charge passed through the electrolyte
Explanation: Faraday’s first law states that the mass of substance deposited at an electrode is proportional to the total electric charge (in coulombs) passed through the cell.
MCQ 16: Factors Affecting Electrode Potential
Question: Which factor does NOT affect the electrode potential of a half-cell?
A) Temperature
B) Concentration of ions
C) Size of the electrode
D) Pressure of gases
Answer: C) Size of the electrode
Explanation: While temperature, concentration, and pressure influence electrode potential, the physical size of the electrode does not directly affect the electrode potential.
MCQ 17: Electrolytic Cell
Question: In an electrolytic cell, what role does the power supply play?
A) It allows for spontaneous reactions to occur.
B) It drives the non-spontaneous reaction.
C) It generates heat for the reaction.
D) It provides the necessary ions for conduction.
Answer: B) It drives the non-spontaneous reaction.
Explanation: The power supply in an electrolytic cell provides the necessary energy to drive a non-spontaneous chemical reaction by forcing electrons through the circuit.
MCQ 18: Types of Electrolytes
Question: Which type of electrolyte fully dissociates into ions in solution?
A) Strong electrolyte
B) Weak electrolyte
C) Nonelectrolyte
D) Solvent
Answer: A) Strong electrolyte
Explanation: Strong electrolytes, such as sodium chloride, fully dissociate into ions when dissolved in water, resulting in high conductivity.
MCQ 19: pH and Cell Potential
Question: How does increasing the acidity (lowering pH) of a solution affect the cell potential of an electrochemical cell involving hydrogen ions?
A) Increases the cell potential
B) Decreases the cell potential
C) Has no effect on cell potential
D) It depends on the temperature
Answer: A) Increases the cell potential
Explanation: Increasing the concentration of hydrogen ions (by lowering pH) in a half-cell reaction involving H⁺ ions increases the reaction quotient, thus increasing the cell potential according to the Nernst equation.
MCQ 20: Conductance Units
Question: What is the SI unit of electrical conductance?
A) Ohm
B) Siemens
C) Volt
D) Ampere
Answer: B) Siemens
Explanation: The SI unit of conductance is Siemens (S), which is the reciprocal of resistance measured in ohms.
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