Oxidation and Reduction (Redox): JAMB Chemistry Questions, Answers & Notes

What Oxidation and Reduction (Redox) covers in the JAMB Chemistry syllabus

Redox reactions involve simultaneous oxidation and reduction. Oxidation is loss of electrons (OIL), gain of oxygen, or loss of hydrogen; reduction is gain of electrons (RIG), loss of oxygen, or gain of hydrogen. An oxidising agent oxidises another substance and is itself reduced (e.g. KMnO₄); a reducing agent donates electrons and is itself oxidised (e.g. H₂, C). Oxidation numbers help track electrons: a free element is 0, oxygen is usually −2, hydrogen +1. An increase in oxidation number means oxidation, a decrease means reduction. Example: in Zn + Cu²⁺ → Zn²⁺ + Cu, zinc is oxidised and copper ions are reduced.

For Oxidation and Reduction (Redox), JAMB expects you to be able to:

• Define oxidation and reduction by electrons, oxygen and hydrogen
• Identify oxidising and reducing agents in redox reactions
• Assign and use oxidation numbers

Key facts & revision notes: Oxidation and Reduction (Redox)

These are the recurring points our Oxidation and Reduction (Redox) questions test — revise them until each feels automatic, then practise the questions above to lock them in.

• Oxidation is loss of electrons (OIL: Oxidation Is Loss).
• Reduction is gain of electrons (RIG: Reduction Is Gain).
• In terms of oxygen, oxidation is the addition (gain) of oxygen.
• An oxidising agent oxidises another substance and is itself reduced.
• A reducing agent donates electrons to another substance and is itself oxidised.
• An element in its free state has an oxidation number of 0.
• Oxygen usually has an oxidation number of −2 (except in peroxides and with fluorine).
• Hydrogen is usually +1 (−1 only in metal hydrides).
• In H₂SO₄: 2(+1) + S + 4(−2) = 0 → S = +6.
• Oxidation and reduction always occur together in a redox reaction.
• Zn loses electrons (Zn → Zn²⁺), so it is oxidised (and is the reducing agent).
• Cu²⁺ gains electrons (Cu²⁺ → Cu), so it is reduced (and is the oxidising agent).
• Na is +1, so Cl must be −1 for the compound to be neutral.
• Potassium permanganate (KMnO₄) is a strong, common oxidising agent.
• Hydrogen (and carbon) are common reducing agents.
• Rusting involves iron gaining oxygen (losing electrons), so iron is oxidised.
• In KMnO₄: (+1) + Mn + 4(−2) = 0 → Mn = +7.
• An increase in oxidation number means loss of electrons — oxidation.
• A decrease in oxidation number means gain of electrons — reduction.
• In terms of hydrogen, reduction is the addition of hydrogen.
• OIL RIG: Oxidation Is Loss, Reduction Is Gain (of electrons).
• Reduction removes oxygen from a substance.
• Oxidation removes hydrogen (or adds oxygen / removes electrons).
• For a simple ion, oxidation number = ionic charge.

Worked examples

Three Oxidation and Reduction (Redox) questions with the answer and a short explanation, so you can see how the topic is set before you practise the full set.

How Oxidation and Reduction (Redox) is tested in JAMB Chemistry

Our Oxidation and Reduction (Redox) bank holds 40 questions (1 easy, 23 medium, 16 hard). JAMB Chemistry typically returns to Oxidation and Reduction (Redox) year after year, so steady practice on this topic is high-value revision. Questions are multiple-choice with four options, and at UTME pace you get roughly 40 seconds each — which is why timed practice matters.

How to answer Oxidation and Reduction (Redox) questions

Work the stem first and predict the answer before you look at the options; then eliminate the ones that contradict the key facts above. Watch for “which is not…”, “all of the above” and “except” style stems, which are where rushed candidates lose easy marks on Oxidation and Reduction (Redox). If a calculation or a precise definition is involved, work it from first principles rather than guessing from a half-remembered rule. When two options look right, re-read the stem for the qualifier that separates them — JAMB rarely repeats an option by accident. If you are still unsure, eliminate the two weakest choices to lift your odds, flag the question, and move on; never burn a full minute on one Chemistry item when the exam gives you about forty seconds each. Then come back to flagged questions with whatever time remains. The single most reliable way to get faster at Oxidation and Reduction (Redox) is repeated timed practice, so use the button above until the recurring patterns feel automatic.

Common mistakes to avoid in Oxidation and Reduction (Redox)

The errors that cost marks on Oxidation and Reduction (Redox) are usually careless rather than conceptual: misreading a negative stem, confusing two similar terms, or rushing a definition you actually know. Candidates also over-rely on “expo” and last-minute cramming instead of understanding the topic — which fails the moment JAMB rephrases a familiar idea. Treat every option as a claim to be checked against the facts above, keep your working tidy for any calculation, and don’t change a considered answer on a hunch. Above all, revise Oxidation and Reduction (Redox) actively by answering questions, not just by re-reading notes — recall under time is what the exam rewards.

Frequently asked questions

Is Oxidation and Reduction (Redox) part of the JAMB Chemistry syllabus?

Yes. Oxidation and Reduction (Redox) is a recognised topic in the JAMB Chemistry syllabus, covering define oxidation and reduction by electrons, oxygen and hydrogen. You should be able to recall its key facts and apply them to multiple-choice questions.

How many Oxidation and Reduction (Redox) questions can I practise on Belmadeng?

There are 40 original, JAMB-standard Oxidation and Reduction (Redox) questions in our free bank, each with the correct answer and a worked explanation. You can practise them untimed or as a timed test.

What are the most important points to know about Oxidation and Reduction (Redox)?

Redox reactions involve simultaneous oxidation and reduction. Oxidation is loss of electrons (OIL), gain of oxygen, or loss of hydrogen; reduction is gain of electrons (RIG), loss of oxygen, or gain of hydrogen. An oxidising agent oxidises another substance and is itself reduced (e.g. KMnO₄); a redu…

How do I answer Oxidation and Reduction (Redox) questions quickly in JAMB?

Read the stem carefully, eliminate clearly wrong options, and match the remaining choices to the key facts for Oxidation and Reduction (Redox). Practising timed Oxidation and Reduction (Redox) questions builds the speed you need for UTME's pace of about 40 seconds per question.

Are these JAMB Chemistry Oxidation and Reduction (Redox) questions past questions or original?

They are original questions written to JAMB (UTME) standard and mapped to the official syllabus — not reproduced past papers. This keeps them legal to use freely while closely mirroring how the real exam tests the topic.

Where can I practise Oxidation and Reduction (Redox) questions free without signing up?

Right here — tap “Start Oxidation and Reduction (Redox) practice” on this page to begin instantly. Belmadeng's CBT practice is completely free and needs no sign-up, download or subscription.

About these questions: original, JAMB-standard items written from the official UTME Chemistry syllabus (last reviewed 2026-09-18). Belmadeng is an independent study platform and is not affiliated with JAMB. Spotted an error? Use the report link.