Skip to main content

Electrochemistry MCQs for MDCAT Practice

Chemistry section, Electrochemistry chapter. Up to eight free sample questions, each with the correct answer and a worked explanation. The full chapter opens in the app.

The bank has 899 active questions on this chapter. Your first 500 practice attempts are free, and every attempt includes a worked explanation.

  1. Question 1
    A chemist in a specialty chemical plant is reviewing reactions that involve disproportionation, where the same element is both oxidized and reduced. This process is useful for synthesizing compounds with intermediate oxidation states from a single reactant. The chemist examines four possible industrial reactions. Which of the following reactions is an example of a disproportionation redox reaction?
    • 2Na2S2O3(aq) + I2(s) → Na2S4O6(aq) + 2NaI(aq)
    • 2FeCl3(aq) + H2S(s) → 2FeCl2 (aq) + 2HCl(aq) + S(s) (correct answer)
    • P4 (s)+ 3NaOH(l) + 3H2O(aq) → 3NaH2PO2(aq) + PH3(g)
    • 2KMnO4(aq) + 8H2SO4(aq) + 10FeSO4(aq) → K2SO4(aq) + 2MnSO4(aq) + 5Fe2(SO4)3(aq) +8H2O(l)
    Correct answer: B
    Identify disproportionation redox reactions where an element is simultaneously oxidized and reduced, a key concept in electrochemistry and synthesis.
  2. Question 2
    In Kolbe's electrolysis, which specific event creates the carbon-carbon pi-bond?
    • Cathode reduction
    • Metal oxidation
    • NaOH formation
    • Radical coupling (correct answer)
    Correct answer: D
    Kolbe's electrolysis forms C-C bonds via radical coupling, not simple electrode reactions or salt formation.
  3. Question 3
    The standard redox potential for the half-cell reaction Fe3+ + e− → Fe2+ is +0.77 V.Which cell would be used to determine this standard value?
    • Fe electrode in 1 mol dm−3 Fe3+ against Fe electrode in 1 mol dm−3 Fe2+
    • Pt electrode in 1 mol dm−3 Fe3+ against Pt electrode in 1 mol dm−3 Fe2+
    • Fe electrode in a solution containing 1 mol dm−3 Fe3+ and 1 mol dm−3 Fe2+ against a standard hydrogen electrode
    • Pt electrode in a solution containing 1 mol dm−3 Fe3+ and 1 mol dm−3 Fe2+ against a standard hydrogen electrode (correct answer)
    Correct answer: D
    Determining standard redox potentials requires a reference electrode, like the SHE, and an inert electrode to facilitate electron transfer for non-metal redox couples.
  4. Question 4
    In balancing, it is very important to identify the substance whose:
    • Physical state is changed
    • Oxidation number is changed (correct answer)
    • Enthalpy is changed
    • All of these
    Correct answer: B
    Balancing redox reactions hinges on tracking electron transfer, which is directly indicated by changes in oxidation numbers.
  5. Question 5
    Electrogravimetry achieves separation and quantification by driving which process at a working electrode via the passage of a controlled electrical current?
    • Deposition of the analyte (correct answer)
    • Selective oxidation of the solvent
    • Solution conductance variation
    • Potential shift measurement
    Correct answer: A
    Electrogravimetry quantifies an analyte by selectively plating or depositing it onto a working electrode via an applied current, followed by mass measurement.
  6. Question 6
    This one is liberated at the anode during clectrolysis of brine in diaphragm cellis:
    • H2
    • Na
    • Cl2 (correct answer)
    • O2
    Correct answer: C
    Electrolysis of brine in a diaphragm cell liberates Cl2 gas at the anode due to the higher oxidation potential of chloride ions compared to water.
  7. Question 7
    In electrochemical cells, reduction takes place at:
    • Anode
    • Cathode (correct answer)
    • At the surface of the electrolyte
    • None of these
    Correct answer: B
    Reduction, the gain of electrons, always occurs at the cathode in electrochemical cells, a fundamental principle of electrochemistry.
  8. Question 8
    Which of the following element same oxidation number in all compounds?
    • Oxygen
    • Fluorine (correct answer)
    • chlorine
    • Both (A) & (C)
    Correct answer: B
    Fluorine consistently exhibits a -1 oxidation state due to its extreme electronegativity, unlike oxygen and chlorine which have variable oxidation states.

Practise all 899 Electrochemistry questions

A free account keeps your correct, incorrect and unseen questions separate, and shows the explanation after every attempt.

Create a free account

Read the full Electrochemistry chapter notes: Electrochemistry notes. Or browse every chapter.