Q.1 Which of the following represents the correct cell notation for a Daniell cell?
Zn | Zn2+ || Cu2+ | Cu
Cu | Cu2+ || Zn2+ | Zn
Zn || Cu
Cu | Zn || Zn2+ | Cu2+
Explanation - In a Daniell cell, zinc is the anode (oxidation occurs) and copper is the cathode (reduction occurs). The single vertical line represents a phase boundary, and double vertical lines represent the salt bridge.
Correct answer is: Zn | Zn2+ || Cu2+ | Cu
Q.2 What is the standard electrode potential (E°) of a hydrogen electrode?
0 V
1 V
0.5 V
-0.5 V
Explanation - By definition, the standard hydrogen electrode (SHE) has a potential of 0 V at all temperatures.
Correct answer is: 0 V
Q.3 Which of the following metals will not liberate hydrogen from dilute acids?
Zn
Fe
Cu
Mg
Explanation - Copper is below hydrogen in the electrochemical series, so it does not react with dilute acids to liberate hydrogen.
Correct answer is: Cu
Q.4 Faraday's first law of electrolysis states that:
The amount of substance deposited is proportional to the quantity of electricity passed
The amount of substance deposited is inversely proportional to the current
The current is independent of deposited substance
Electrolysis occurs only with electrolytes
Explanation - Faraday's first law states that mass (m) of substance deposited at an electrode is directly proportional to the total electric charge (Q) passed through the electrolyte.
Correct answer is: The amount of substance deposited is proportional to the quantity of electricity passed
Q.5 Which of the following is used as the reference electrode in electrochemical measurements?
Calomel electrode
Silver-silver chloride electrode
Standard hydrogen electrode
All of the above
Explanation - Various reference electrodes are used for different purposes. SHE, calomel, and silver-silver chloride electrodes are common reference electrodes.
Correct answer is: All of the above
Q.6 During electrolysis of molten NaCl, which of the following occurs at the cathode?
Na+ is reduced to Na
Cl- is reduced to Cl2
Na+ is oxidized to Na2
Cl- is oxidized to Cl2
Explanation - At the cathode, cations gain electrons (reduction). Na+ is reduced to sodium metal.
Correct answer is: Na+ is reduced to Na
Q.7 Which of the following has the highest standard reduction potential?
Ag+ + e- → Ag
Cu2+ + 2e- → Cu
Zn2+ + 2e- → Zn
Fe2+ + 2e- → Fe
Explanation - Silver has the highest tendency to gain electrons among the options, hence the highest standard reduction potential.
Correct answer is: Ag+ + e- → Ag
Q.8 Which term is used to describe the voltage of an electrochemical cell under standard conditions?
Cell constant
Electrode potential
Standard EMF
Conductivity
Explanation - The EMF of a cell under standard conditions (1 M, 1 atm, 298 K) is called the standard EMF.
Correct answer is: Standard EMF
Q.9 In an electrolytic cell, the anode is always:
Positive
Negative
Neutral
Can be either
Explanation - In an electrolytic cell, the anode is connected to the positive terminal, where oxidation occurs.
Correct answer is: Positive
Q.10 Which of the following affects the rate of electrolysis?
Nature of electrolyte
Concentration of ions
Current passed
All of the above
Explanation - Electrolysis rate depends on current, electrolyte type, and ion concentration.
Correct answer is: All of the above
Q.11 What is the value of Faraday constant (approximately)?
96500 C/mol
96485 C/mol
95000 C/mol
100000 C/mol
Explanation - Faraday constant is the charge of one mole of electrons, equal to 96485 coulombs per mole.
Correct answer is: 96485 C/mol
Q.12 In the electrolysis of aqueous CuSO4 using copper electrodes, the mass of the anode:
Increases
Decreases
Remains unchanged
Depends on current
Explanation - The copper anode dissolves into Cu2+ ions during electrolysis, so its mass decreases.
Correct answer is: Decreases
Q.13 Which of the following is the strongest oxidizing agent in aqueous solution?
F2
Cl2
Br2
I2
Explanation - Fluorine has the highest electronegativity and standard reduction potential, making it the strongest oxidizing agent.
Correct answer is: F2
Q.14 Electroplating is carried out mainly to:
Increase conductivity
Increase corrosion resistance
Change color
All of the above
Explanation - Electroplating can improve corrosion resistance, conductivity, and aesthetic appeal.
Correct answer is: All of the above
Q.15 Which law relates the amount of substance deposited to the equivalent weight and charge passed?
Faraday's first law
Faraday's second law
Ohm's law
Kirchhoff's law
Explanation - Faraday's second law states that when the same quantity of electricity is passed through different electrolytes, the amount of substance deposited is proportional to their equivalent weights.
Correct answer is: Faraday's second law
Q.16 Which is the main reaction at the cathode during electrolysis of water?
2H2O + 2e- → H2 + 2OH-
2H2O → O2 + 4H+ + 4e-
H2O → H+ + OH-
None of these
Explanation - At the cathode, water is reduced to hydrogen gas and hydroxide ions.
Correct answer is: 2H2O + 2e- → H2 + 2OH-
Q.17 Which electrolyte is used in the Hall-Héroult process for the extraction of aluminum?
Al2O3 in molten cryolite
NaCl
CaCl2
MgO in molten salt
Explanation - Aluminum oxide is dissolved in molten cryolite and electrolyzed to produce aluminum metal.
Correct answer is: Al2O3 in molten cryolite
Q.18 Which metal is obtained by electrolysis of its fused chloride?
Na
Mg
Al
All of the above
Explanation - Electrolysis of molten salts is used to extract highly reactive metals like Na, Mg, and Al.
Correct answer is: All of the above
Q.19 A cell with Zn | Zn2+ || Cu2+ | Cu has an EMF of 1.1 V. If the cell is reversed, what is the EMF?
-1.1 V
0 V
1.1 V
-0.55 V
Explanation - Reversing the cell reverses the direction of electron flow, so the EMF changes sign.
Correct answer is: -1.1 V
Q.20 Which of the following solutions is used in the standard calomel electrode?
KCl saturated
NaCl saturated
HCl solution
NaOH solution
Explanation - The calomel electrode contains Hg/Hg2Cl2 in saturated KCl solution as the reference electrode.
Correct answer is: KCl saturated
Q.21 The corrosion of iron in presence of water and oxygen produces:
Fe2O3
FeO
Fe3O4
Fe(OH)2
Explanation - Iron reacts with oxygen and water to form rust, primarily Fe2O3·xH2O.
Correct answer is: Fe2O3
Q.22 In which type of cell is chemical energy converted into electrical energy?
Galvanic cell
Electrolytic cell
Both
None
Explanation - A galvanic cell generates electricity from spontaneous redox reactions.
Correct answer is: Galvanic cell
Q.23 Which of the following is an example of a primary cell?
Leclanché cell
Lead-acid battery
Nickel-cadmium battery
Lithium-ion battery
Explanation - A primary cell cannot be recharged. The Leclanché cell is a common primary battery.
Correct answer is: Leclanché cell
Q.24 In a voltaic cell, which electrode undergoes oxidation?
Anode
Cathode
Both
Neither
Explanation - In a voltaic cell, oxidation occurs at the anode, and reduction occurs at the cathode.
Correct answer is: Anode
Q.25 During electrolysis, the efficiency of deposition can be increased by:
Increasing current density
Decreasing temperature
Using inert electrodes
All of the above
Explanation - Deposition efficiency depends on current density, temperature, and electrode type.
Correct answer is: All of the above