Q.1 Which of the following is the correct statement of Faraday's first law of electrolysis?
The amount of substance deposited is proportional to the square of current
The amount of substance deposited is proportional to the charge passed
The amount of substance deposited is independent of the charge passed
The amount of substance deposited depends on the nature of the electrolyte only
Explanation - Faraday's first law states that the mass of substance deposited or liberated at an electrode is directly proportional to the quantity of electric charge passed through the electrolyte.
Correct answer is: The amount of substance deposited is proportional to the charge passed
Q.2 What is the SI unit of electric charge?
Coulomb
Ampere
Volt
Ohm
Explanation - The SI unit of electric charge is the Coulomb (C). One Coulomb is the charge transported by a constant current of one ampere in one second.
Correct answer is: Coulomb
Q.3 In a galvanic cell, the electrode where oxidation occurs is called:
Cathode
Anode
Electrolyte
Salt bridge
Explanation - Oxidation occurs at the anode in a galvanic cell, while reduction occurs at the cathode.
Correct answer is: Anode
Q.4 Which of the following is a primary standard for measuring the strength of potassium permanganate solution?
Oxalic acid
Sulfuric acid
Sodium hydroxide
Hydrochloric acid
Explanation - Oxalic acid is used as a primary standard to standardize KMnO₄ solution because it is pure, stable, and reacts stoichiometrically with KMnO₄.
Correct answer is: Oxalic acid
Q.5 What is the standard electrode potential of a standard hydrogen electrode (SHE)?
0 V
1 V
-1 V
0.5 V
Explanation - The standard hydrogen electrode is assigned a potential of 0 volts under standard conditions and serves as a reference for measuring electrode potentials.
Correct answer is: 0 V
Q.6 Which type of cell converts chemical energy directly into electrical energy?
Galvanic cell
Electrolytic cell
Voltaic cell
Both A and C
Explanation - Galvanic (or voltaic) cells convert chemical energy directly into electrical energy through spontaneous redox reactions.
Correct answer is: Both A and C
Q.7 In an electrolytic cell, the electrode connected to the positive terminal of the battery is:
Anode
Cathode
Both Anode and Cathode
None of these
Explanation - In an electrolytic cell, the anode is connected to the positive terminal and oxidation occurs there, while the cathode is connected to the negative terminal where reduction occurs.
Correct answer is: Anode
Q.8 Which of the following electrolytes would conduct electricity in molten state but not in solid state?
Sodium chloride
Copper
Sulfur
Water
Explanation - Ionic compounds like NaCl conduct electricity when molten because ions are free to move, but they do not conduct in solid state as ions are fixed in the lattice.
Correct answer is: Sodium chloride
Q.9 In the electrolysis of water, which gas is produced at the cathode?
Oxygen
Hydrogen
Chlorine
Nitrogen
Explanation - At the cathode, reduction occurs: 2H⁺ + 2e⁻ → H₂. Thus hydrogen gas is produced.
Correct answer is: Hydrogen
Q.10 The Nernst equation is used to calculate:
Cell potential under non-standard conditions
Standard electrode potential
Resistance of electrolyte
Current in the cell
Explanation - The Nernst equation relates the electrode potential of a cell to the standard electrode potential, temperature, and concentrations of the ions involved.
Correct answer is: Cell potential under non-standard conditions
Q.11 Which of the following metals cannot be obtained by electrolysis of its aqueous salt solution?
Copper
Aluminum
Zinc
Sodium
Explanation - Sodium cannot be obtained by electrolysis of aqueous solution because water is preferentially reduced to hydrogen. Sodium is obtained by molten salt electrolysis.
Correct answer is: Sodium
Q.12 The cell reaction in a Daniell cell is:
Zn + Cu²⁺ → Zn²⁺ + Cu
Cu + Zn²⁺ → Cu²⁺ + Zn
Zn²⁺ + Cu → Zn + Cu²⁺
2Zn + O₂ → 2ZnO
Explanation - In a Daniell cell, zinc is oxidized and copper is reduced: Zn → Zn²⁺ + 2e⁻ and Cu²⁺ + 2e⁻ → Cu.
Correct answer is: Zn + Cu²⁺ → Zn²⁺ + Cu
Q.13 During electrolysis, the efficiency of deposition is maximum when:
Current is very high
Current is very low
Current density is optimum
Temperature is very high
Explanation - Excessively high or low current reduces deposition efficiency. Maximum efficiency occurs at an optimum current density.
Correct answer is: Current density is optimum
Q.14 In a concentration cell, the electromotive force (EMF) depends on:
Nature of electrolyte
Temperature and concentration difference
Size of electrodes
Standard electrode potentials only
Explanation - A concentration cell has identical electrodes but different ion concentrations. EMF arises due to the concentration difference and depends on temperature as per the Nernst equation.
Correct answer is: Temperature and concentration difference
Q.15 The term 'overvoltage' in electrochemistry refers to:
Extra voltage required beyond the theoretical value
Voltage lost due to resistance
Standard electrode potential
Voltage in a galvanic cell
Explanation - Overvoltage is the additional potential required to drive a non-spontaneous electrochemical reaction at a desired rate, often due to slow kinetics.
Correct answer is: Extra voltage required beyond the theoretical value
Q.16 In electroplating, the object to be plated acts as:
Anode
Cathode
Salt bridge
Electrolyte
Explanation - The object to be plated is connected to the negative terminal and attracts cations from the electrolyte. Reduction occurs at the cathode.
Correct answer is: Cathode
Q.17 Which of the following increases the conductivity of an electrolyte solution?
Increasing the concentration of ions
Increasing temperature
Both A and B
Decreasing ion concentration
Explanation - Conductivity depends on the number of ions and their mobility. Increasing concentration or temperature increases conductivity.
Correct answer is: Both A and B
Q.18 Electrochemical series is a list of elements arranged in the order of their:
Atomic number
Standard electrode potentials
Ionization energies
Electronegativity
Explanation - The electrochemical series arranges elements in order of increasing standard electrode potentials, predicting their tendency to get oxidized or reduced.
Correct answer is: Standard electrode potentials
Q.19 Which of the following is used in dry cells as an oxidizing agent?
MnO₂
Zn
Graphite
NH₄Cl
Explanation - In a dry cell, MnO₂ acts as the depolarizer (oxidizing agent) and removes the electrons released from zinc oxidation.
Correct answer is: MnO₂
Q.20 During electrolysis of molten NaCl, the product at the anode is:
Chlorine
Sodium
Hydrogen
Oxygen
Explanation - At the anode, Cl⁻ ions are oxidized to chlorine gas: 2Cl⁻ → Cl₂ + 2e⁻.
Correct answer is: Chlorine
Q.21 Which of the following can be used to protect iron from rusting by sacrificial method?
Zinc
Copper
Silver
Aluminum
Explanation - Zinc corrodes preferentially and protects iron from rusting in the sacrificial protection method.
Correct answer is: Zinc
Q.22 The relation between the Gibbs free energy change and EMF of a cell is:
ΔG = -nFE
ΔG = nFE
ΔG = n/R
ΔG = E/nF
Explanation - ΔG (change in Gibbs free energy) is related to EMF by ΔG = -nFE, where n is the number of moles of electrons and F is Faraday's constant.
Correct answer is: ΔG = -nFE
Q.23 The decomposition potential of an electrolytic cell is:
The theoretical voltage required for electrolysis
The voltage actually applied to cause electrolysis
The standard electrode potential
EMF of a galvanic cell
Explanation - Decomposition potential is the minimum voltage that must be applied to an electrolytic cell to initiate the decomposition reaction, often higher than theoretical due to overvoltage.
Correct answer is: The voltage actually applied to cause electrolysis
Q.24 Which of the following represents a reversible electrode process?
Zn²⁺ + 2e⁻ ⇌ Zn
Cu + H₂SO₄ → CuSO₄ + H₂
Fe + O₂ → Fe₂O₃
C + O₂ → CO₂
Explanation - A reversible electrode process is one that can proceed in both directions depending on the applied potential. Zn²⁺/Zn redox is reversible.
Correct answer is: Zn²⁺ + 2e⁻ ⇌ Zn