91. The Nernst equation relates the cell potential to:
- a) Temperature
- b) Concentration of reactants and products
- c) Pressure
- d) Both a and b
Answer: d) Both a and b
Explanation: The Nernst equation relates the cell potential to temperature and the concentrations of the reactants and products, allowing the calculation of the cell potential under non-standard conditions.
92. Which of the following ions is responsible for the corrosion of iron?
- a) Chloride ions
- b) Sodium ions
- c) Sulfate ions
- d) Nitrate ions
Answer: a) Chloride ions
Explanation: Chloride ions (Cl⁻) are highly corrosive to metals like iron because they accelerate the oxidation process, leading to rust formation.
93. What is the major disadvantage of a lithium-ion battery?
- a) High self-discharge rate
- b) Limited charge cycles
- c) Prone to memory effect
- d) High cost
Answer: d) High cost
Explanation: While lithium-ion batteries are highly efficient and have long charge cycles, their high cost is a major disadvantage compared to other types of batteries.
94. Which of the following methods is used to prevent the corrosion of iron?
- a) Galvanization
- b) Oxidation
- c) Reduction
- d) Electrolysis
Answer: a) Galvanization
Explanation: Galvanization involves coating iron or steel with a layer of zinc to prevent corrosion.
95. The rate of corrosion is least in:
- a) Dry air
- b) Wet air
- c) Saltwater
- d) Moist air
Answer: a) Dry air
Explanation: Corrosion occurs faster in the presence of moisture and electrolytes. Dry air has the least moisture and hence the least corrosion rate.
96. The emf of a standard cell depends on:
- a) The nature of the electrodes and electrolytes
- b) The current flowing through the cell
- c) The size of the electrodes
- d) The resistance of the cell
Answer: a) The nature of the electrodes and electrolytes
Explanation: The electromotive force (emf) of a standard cell depends on the nature of the electrodes and the electrolytes used in the cell.
97. The amount of charge required to deposit 1 mole of a substance at an electrode during electrolysis is given by:
- a) Faraday’s constant
- b) Avogadro’s number
- c) Coulomb’s law
- d) Planck’s constant
Answer: a) Faraday’s constant
Explanation: Faraday’s constant (approximately 96,500 C/mol) represents the amount of charge required to deposit 1 mole of a substance during electrolysis.
98. Which of the following reactions occurs at the cathode in an electrochemical cell?
- a) Oxidation
- b) Reduction
- c) Electron loss
- d) Proton transfer
Answer: b) Reduction
Explanation: In an electrochemical cell, reduction (gain of electrons) occurs at the cathode.
99. In a fuel cell, the oxidizing agent is typically:
- a) Oxygen
- b) Hydrogen
- c) Nitrogen
- d) Carbon dioxide
Answer: a) Oxygen
Explanation: In most fuel cells, oxygen acts as the oxidizing agent, accepting electrons to form water as a product.
100. What is the purpose of the salt bridge in a galvanic cell?
- a) To maintain electrical neutrality in the solution
- b) To increase the cell voltage
- c) To separate the anode and cathode physically
- d) To allow the flow of electrons between electrodes
Answer: a) To maintain electrical neutrality in the solution
Explanation: The salt bridge allows ions to flow between the two half-cells to maintain charge balance, ensuring the continuous flow of electrons and maintaining the cell’s electrical neutrality
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