In the external circuit of a galvanic cell, electrons flow ____
Correct answer A. from the anode to the cathode
Topic / 40 questions
Electrochemistry MCQs
Electrochemistry MCQs are multiple-choice questions on redox reactions, oxidation numbers, balancing redox equations, electrode potentials and electrochemical cells. They follow the MDCAT chemistry curriculum, and every question on MCQs360 shows its correct answer instantly so you can practise oxidation number and emf calculations with immediate checking.
- Gases 40
- Liquids 40
- Solids 40
- Chemical Equilibrium 40
- Reaction Kinetics 40
- Thermochemistry and Energetics 40
- Electrochemistry 40
- Fundamental Concepts of Chemistry 40
- Atomic Structure 39
- Chemical Bonding 39
- Alcohols and Phenols 38
- Industrial Chemistry 37
- Aldehydes and Ketones 37
- Alkyl Halides 37
- s- and p-Block Elements 37
- Chemistry of Hydrocarbons 36
- Fundamental Principles of Organic Chemistry 36
- Carboxylic Acids 36
- Transition Elements 35
- Macromolecules 35
What is the oxidation number of sulphur in H₂SO₄?
Correct answer A. +6
What is the oxidation number of chlorine in potassium chlorate, KClO₃?
Correct answer A. +5
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What is the oxidation number of hydrogen in sodium hydride, NaH?
Correct answer C. −1
What is the oxidation number of oxygen in hydrogen peroxide, H₂O₂?
Correct answer C. −1
What is the average oxidation number of carbon in glucose, C₆H₁₂O₆?
Correct answer A. 0
In the reaction 2Fe³⁺ + Sn²⁺ → 2Fe²⁺ + Sn⁴⁺, which species is the reducing agent?
Correct answer C. Sn²⁺
Which reaction is an example of disproportionation?
Correct answer B. 2H₂O₂ → 2H₂O + O₂
When the equation MnO₂ + HCl → MnCl₂ + Cl₂ + H₂O is balanced, what is the coefficient of HCl?
Correct answer C. 4
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In neutral or weakly basic solution MnO₄⁻ is reduced to MnO₂. What is the change in the oxidation number of manganese?
Correct answer A. Decrease by 3
During the electrolysis of molten sodium chloride, what is formed at the cathode and the anode respectively?
Correct answer D. Sodium metal and chlorine gas
In the electrolysis of concentrated aqueous NaCl (brine), which product is formed at the cathode?
Correct answer B. Hydrogen gas
Which metal is the strongest reducing agent?
Correct answer C. Lithium
Using E°(Fe²⁺/Fe) = −0.44 V and E°(Cu²⁺/Cu) = +0.34 V, which reaction is spontaneous under standard conditions?
Correct answer B. Fe + Cu²⁺ → Fe²⁺ + Cu
Given E°(Zn²⁺/Zn) = −0.76 V and E°(Ag⁺/Ag) = +0.80 V, what is the standard emf of a zinc-silver cell?
Correct answer D. 1.56 V
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What is the average oxidation number of iron in Fe₃O₄?
Correct answer A. +8/3
What does a positive value of E°cell indicate for a redox reaction written in a particular direction?
Correct answer D. The reaction is spontaneous in that direction under standard conditions
What are the oxidation numbers of the two nitrogen atoms in ammonium nitrate, NH₄NO₃?
Correct answer A. −3 and +5
Which of the following reactions is NOT a redox reaction?
Correct answer B. NaCl + AgNO₃ → AgCl + NaNO₃
Which statement defines the electrode potential of a metal electrode?
Correct answer A. The potential difference set up between the metal and a solution of its own ions
About Electrochemistry MCQs
A large part of this topic is about oxidation numbers: finding the oxidation state of an element in compounds and ions such as KMnO₄, K₂Cr₂O₇, NH₄NO₃, OF₂ and Fe₃O₄, identifying oxidising and reducing agents, and recognising which reactions are redox and which are disproportionation. Balancing equations by the oxidation number change method and finding mole ratios in reactions such as MnO₄⁻ or Cr₂O₇²⁻ with Fe²⁺ also appear. The second part covers electrodes and cells: the anode and cathode, the standard hydrogen electrode, standard electrode potentials, the electrochemical series and calculating the standard emf of cells such as the Daniell cell. Questions also ask which metals can liberate hydrogen from dilute acids.
Key facts to remember
- Oxidation is loss of electrons or an increase in oxidation number; reduction is gain of electrons or a decrease in oxidation number.
- Oxygen usually has an oxidation number of −2, but it is +2 in OF₂ and −1 in peroxides.
- Manganese is +7 in KMnO₄ and chromium is +6 in K₂Cr₂O₇.
- The standard hydrogen electrode is assigned an electrode potential of exactly 0.00 V.
- E°cell = E°cathode − E°anode; for the Daniell cell, 0.34 − (−0.76) = 1.10 V.
- Oxidation always occurs at the anode and reduction at the cathode.
Exams that include Electrochemistry MCQs
Pakistan
- MDCAT
- ECAT
- NUMS
- AKU
- FSc boards
India
- NEET
- JEE Main
Bangladesh
- HSC
- Medical Admission Test
How to prepare for Electrochemistry MCQs
- Learn the fixed oxidation number rules (group 1, group 2, fluorine, hydrogen, oxygen) and their exceptions.
- For mole ratio questions, balance electrons first: MnO₄⁻ gains 5 electrons and Cr₂O₇²⁻ gains 6.
- Use 'anode oxidation, cathode reduction' and calculate E°cell as cathode minus anode.
- Remember that a metal with a negative standard electrode potential can usually liberate hydrogen from dilute acids.
Frequently asked questions
What does the MDCAT syllabus include in Electrochemistry?
The PMDC MDCAT curriculum covers redox reactions and identifying oxidation and reduction by oxidation number, balancing redox equations by oxidation number change, the cathode, anode, electrode potential and standard hydrogen electrode, and standard electrode potentials.
Which exams ask Electrochemistry MCQs?
Electrochemistry and redox questions appear in MDCAT, ECAT, NUMS and AKU entry tests and in FSc board papers in Pakistan. They are also part of NEET and JEE Main in India and HSC and medical admission tests in Bangladesh.
What is the standard hydrogen electrode?
The standard hydrogen electrode is platinised platinum dipped in a 1 mol dm⁻³ solution of H⁺ ions with hydrogen gas bubbled over it at 1 atm and 298 K. Its potential is defined as 0.00 V, and other electrode potentials are measured against it.
Last reviewed October 2026