Free Electrochemistry MCQs with Answers
696 Electrochemistry MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Electrochemistry describes electron transfer through oxidation and reduction, identifies oxidizing and reducing agents, and applies oxidation numbers to balance redox equations. It also covers electrode potential and the standard hydrogen electrode, which provides the reference for comparing the reduction tendencies of other electrodes.
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Read the Electrochemistry notesFree MDCAT chapter notes with key terms696 questions · page 5 of 35
- A. From cathode to anode in outer circuit
- B. From anode to cathode outside the cell
- C. From cathode to anode inside the cell
- D. both B & C
Explanation: In the external circuit of an electrolytic cell, conventional current flows from the positive anode toward the negative cathode, opposite…
Correct answer: From anode to cathode outside the cell- A. H2 is deposited at cathode
- B. Colour of the solution becomes fade
- C. Cu is deposited at anode
- D. All are possible
Explanation: At the cathode, Cu2+ is preferentially reduced to Cu, while at the platinum anode water is oxidised to oxygen; Cu2+ is therefore removed…
Correct answer: Colour of the solution becomes fade- A. Displacement
- B. Reduction
- C. Disproportionation reaction
- D. Double displacement reaction
Explanation: Hot concentrated caustic soda reacts with chlorine as 3Cl2 + 6NaOH -> 5NaCl + NaClO3 + 3H2O.
Correct answer: Disproportionation reaction- A. Reduction occurs at anode
- B. K+ ion transfer from salt bridge to left beaker of ZnSO4
- C. Oxidation occurs at cathode
- D. Anode is negatively charged
Explanation: In a Zn-Cu galvanic cell, zinc is oxidised at the anode: Zn -> Zn2+ + 2e-.
Correct answer: Anode is negatively charged- A. H2SO4
- B. KMnO4
- C. H2S
- D. K2CrO4
Explanation: H2SO4, KMnO4 and K2CrO4 all contain oxygen and are oxy compounds or oxy salts, whereas H2S is a binary hydride containing no oxygen.
Correct answer: H2S- A. Silver oxide battery
- B. Fuel cell
- C. Nickel cadmium cell
- D. Lead accumulator
Explanation: Nickel-cadmium cells are rechargeable secondary cells that were commonly used in portable electronic devices, including older laptops.
Correct answer: Nickel cadmium cell- A. A
- B. Ag
- C. Both
- D. Neither
Explanation: In an Al-Ag galvanic cell, aluminium is more readily oxidised and acts as the anode, while Ag+ ions are reduced at the silver cathode.
Correct answer: Ag- A. 0.76
- B. -0.76
- C. -0.55
- D. 0.55
Explanation: The standard reduction potential of Zn2+ + 2e- -> Zn is -0.76 V when measured relative to the standard hydrogen electrode.
Correct answer: -0.76- A. to get oxidized
- B. to get reduced
- C. to accept electrons
- D. both B and C
Explanation: A higher standard reduction potential means a greater tendency for a species to gain electrons, so it is more readily reduced and acts as…
Correct answer: both B and C- A. zero
- B. unity
- C. constant
- D. multiple of 1
Explanation: The standard hydrogen electrode is assigned a standard reduction potential of exactly 0 V, and other standard electrode potentials are…
Correct answer: zero- A. New electrode of same element
- B. SHE
- C. 1M solution of ions of respective element
- D. 2M solution of HCI
Explanation: A standard reduction potential is measured by connecting the half-cell to the standard hydrogen electrode, whose potential is defined as 0…
Correct answer: SHE- A. CCu
- B. Ag
- C. Pt
- D. None
Explanation: Platinum is chemically inert and can provide a conducting surface for electron transfer without being consumed in the electrode reaction.
Correct answer: Pt- A. 2M
- B. 1N
- C. 1m
- D. 1M
Explanation: Standard electrode potentials are measured under standard conditions, including a dissolved ionic concentration of 1 M.
Correct answer: 1M- A. 760mm of Hg
- B. 750mm of Hg
- C. 780mm of Hg
- D. 800mm of Hg
Explanation: The standard hydrogen electrode uses hydrogen gas at a standard pressure of 1 atmosphere, which is equal to 760 mm Hg.
Correct answer: 760mm of Hg- A. 1 M ZnO solution
- B. 1 M ZnSO4 solution
- C. 1.5 M ZnSO4 solution
- D. 0.1 M ZnSO4 solution
Explanation: To measure the standard electrode potential of Zn, the Zn2+ activity is taken as 1 M and zinc metal is dipped into a 1 M ZnSO4 solution.
Correct answer: 1 M ZnSO4 solution- A. Oxidation potential
- B. Redox potential
- C. e.m.f of cell
- D. standard reduction potential
Explanation: An oxidising agent accepts electrons, so its tendency to be reduced is measured by its standard reduction potential.
Correct answer: standard reduction potential- A. Ni2+ + Zn -> Zn2+ + Ni
- B. Zn2+ + Ni -> Ni2+ + Zn
- C. Zn2+ + Ni2+ -> Zn + Ni
- D. Zn + Ni -> Zn2+ + Ni2+
Explanation: In the given cell, Zn is oxidized to Zn2+ ions, and Ni2+ ions are reduced to Ni atoms. The anode is Zn, and the cathode is Ni.
Correct answer: Ni2+ + Zn -> Zn2+ + Ni- A. Sulfur gas
- B. Sulfur dioxide
- C. Sulfur trioxide
- D. Hydrogen sulfide
Explanation: When elemental sulfur is burnt, it reacts with oxygen in the air to form sulfur dioxide gas (SO2), as shown by the following equation: S +…
Correct answer: Sulfur trioxide- A. +5
- B. +7
- C. +10
- D. +17
Explanation: To solve this problem, we must balance the redox reaction by ensuring that both mass and charge are conserved.
Correct answer: +17- A. Written with oxidation numbers of constituents
- B. Split into two half reactions
- C. Only oxidation part is written
- D. Only reducing part is written
Explanation: The ion-electron method, or the half-reaction method, is a systematic approach to balancing redox reactions.
Correct answer: Split into two half reactions