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 9 of 35
- A. Zn
- B. Cu
- C. Ag
- D. All equal
Explanation: More negative electrode potential = better reducing agent. Zn (-0.76 V) is most negative.
Correct answer: Zn- A. Internal, cathode → anode
- B. External, anode → cathode
- C. External, cathode → anode
- D. Only through salt bridge
Explanation: Electrons leave the anode and enter the cathode through the external wire.
Correct answer: External, anode → cathode- A. VO²⁺ → V₂O₃
- B. Na → Na⁺
- C. CrO₄²⁻ → Cr₂O₇²⁻
- D. Zn²⁺ → Zn
Explanation: In both the chromate (CrO₄²⁻) and dichromate (Cr₂O₇²⁻) ions, the oxidation state of chromium is +6.
Correct answer: CrO₄²⁻ → Cr₂O₇²⁻- A. Oxidation reaction
- B. Reduction reaction
- C. Disproportionation reaction
- D. Decomposition reaction
Explanation: This is a disproportionation reaction because the same element, chlorine, is simultaneously oxidized and reduced.
Correct answer: Disproportionation reaction- A. MgCl2
- B. BeCl₂
- C. CaCl₂
- D. SrCl₂
Explanation: Due to the small size and high charge density of the Be²⁺ ion, Beryllium chloride (BeCl₂) has a significant degree of covalent character.
Correct answer: BeCl₂- A. Galvanic cell
- B. Concentration cell
- C. Electrolytic cell
- D. Both A and B
Explanation: Electrolytic cell uses external battery → anode is positive.
Correct answer: Electrolytic cell- A. Both half-cell reactions take place simultaneously
- B. Of the resistance of the wire
- C. A reaction does not take place on its own
- D. None of the above
Explanation: A half-cell reaction represents either oxidation or reduction, but not both.
Correct answer: A reaction does not take place on its own- A. Oxidation of copper ions to form copper oxide
- B. Oxidation of sulfate ions to form sulfur trioxide
- C. Oxidation of water to form oxygen gas and hydrogen ions
- D. Oxidation of chloride ions to form chlorine gas
Explanation: At the anode (oxidation), we compare the oxidation potentials of SO₄²⁻ and H₂O.
Correct answer: Oxidation of water to form oxygen gas and hydrogen ions- A. A horizontal line
- B. A straight line with a positive slope passing through the origin
- C. A curve that starts at the origin and curves upwards
- D. A straight line with a negative slope
Explanation: According to Faraday's first law of electrolysis, the mass of a substance deposited is directly proportional to the quantity of charge…
Correct answer: A straight line with a positive slope passing through the origin- A. The electrode of half-cell potential -0.76 V serves as the cathode
- B. The electrode of half-cell potential -0.76 V serves as the anode
- C. The electrode of half-cell potential -0.13 V serves as the anode
- D. The electrode of half-cell potential -0.76 V is the positive electrode
Explanation: In a galvanic (voltaic) cell, the half-cell with the more negative reduction potential will be the site of oxidation and is therefore the…
Correct answer: The electrode of half-cell potential -0.76 V serves as the anode- A. Ampere
- B. Volt
- C. Coulomb
- D. Ohm
Explanation: Volt - because cell potential measures electrical potential difference, which is expressed in volts.
Correct answer: Volt- A. Have no effect
- B. Precipitate Mg metal
- C. Precipitate MgO
- D. Lead to dissolution of Be metal
Explanation: Reactivity in alkali earth metals generally increases down the group. Therefore, Magnesium is more reactive than Beryllium.
Correct answer: Have no effect- A. Cathode and gets reduced
- B. Anode and gets oxidized
- C. Cathode and gets oxidized
- D. Anode but gets reduced
Explanation: In daniel cell zinc electrode is anode where it get oxidized by losing electron.
Correct answer: Anode and gets oxidized- A. Acetic acid
- B. NH₄OH
- C. HCl
- D. Water
Explanation: HCl ionizes completely → strong electrolyte.
Correct answer: HCl- A. Non-spontaneous
- B. Spontaneous
- C. At equilibrium
- D. Impossible
Explanation: E°cell > 0 → spontaneous reaction in galvanic cell.
Correct answer: Spontaneous- A. Zn(s)
- B. Cr(s)
- C. H₂(g)
- D. Fe²⁺(aq)
Explanation: A strong reducing agent is easily oxidized, meaning its corresponding reduction half reaction has the most negative standard reduction…
Correct answer: Zn(s)- A. +1
- B. +2
- C. +3
- D. +6
Explanation: 0.56 dm³ of O₂ at STP is 0.025 moles O₂ evolution at the anode shows 0.1 mol e⁻ passed.0.05 mol Cr deposited at cathode → 0.1 / 0.05 = 2…
Correct answer: +3- A. 0.75
- B. 1.0
- C. 1.5
- D. 3.0
Explanation: The reaction is ClO₃⁻ → ClO₄⁻. The oxidation state of Cl changes from +5 to +7, a loss of 2 electrons.
Correct answer: 1.5- A. 0.2 mole of Cu²⁺ will go into the solution
- B. 560 ml O₂ is liberated
- C. No loss in weight
- D. 2 grams of copper goes into the solution as Cu²⁺
Explanation: When using active electrodes (copper), the anode is oxidized:Cu(s)→ Cu²⁺(aq)+ 2e⁻.
Correct answer: 2 grams of copper goes into the solution as Cu²⁺- A. O₂ & SO₂
- B. SO₂ & O₂
- C. O₂ & H₂
- D. H₂ & O₂
Explanation: In the electrolysis of dilute aqueous solutions, water is often oxidized or reduced in preference to the solute ions.
Correct answer: O₂ & H₂