7.4

Oxides

Cambridge IGCSE Chemistry (0620)  · Unit 7: Acids, bases and salts  · 10 flashcards

Oxides is topic 7.4 in the Cambridge IGCSE Chemistry (0620) syllabus , positioned in Unit 7 — Acids, bases and salts , alongside Acids and bases, Reactions of acids and Preparation of salts.  In one line: A basic oxide reacts with acids to form salts and water.

This topic is examined in Paper 1 (multiple-choice) and Papers 3/4 (theory), plus Paper 5 or Paper 6 (practical / alternative to practical). Past papers from 2022 to 2025 show this topic across undefined questions worth 87 marks (around 1.3% of all Chemistry marks in those years).

The deck below contains 10 flashcards — 2 definitions, 6 key concepts and 1 identification card — covering the precise wording mark schemes reward.  Use the 2 definition cards to lock down command-word answers (define, state), then move on to the concept and application cards to handle explain, describe and compare questions.

Key definition

A 'basic oxide' and provide an example

A basic oxide reacts with acids to form salts and water.

Example: Magnesium oxide (MgO) reacts with hydrochloric acid (HCl) to form magnesium chloride (MgCl2) and water (H2O).

Questions this Oxides deck will help you answer

Key Concept Flip

How are oxides of nitrogen formed in car engines?

Answer Flip

Nitrogen and oxygen from the air react at high temperatures inside the engine, forming oxides of nitrogen (

Example: NO, NO2).
Key Concept Flip

What are two negative environmental impacts of nitrogen oxides released from car engines?

Answer Flip

Nitrogen oxides contribute to acid rain, damaging buildings and ecosystems. They also cause respiratory problems such as asthma.

Example: high concentrations of nitrogen oxides in cities like Los Angeles contribute to smog and respiratory ailments.
Key Concept Flip

How can a metal carbonate be used to produce a metal oxide?

Answer Flip

A metal carbonate can be heated to produce a metal oxide through thermal decomposition. This process releases carbon dioxide gas.

Example: when copper(II) carbonate is heated, it decomposes into copper(II) oxide and carbon dioxide: CuCO3(s) → CuO(s) + CO2(g).
Key Concept Flip

Describe a chemical test to identify if a gas is ammonia (NH3).

Answer Flip

Add aqueous sodium hydroxide or damp red litmus paper to the gas. If ammonia is present, the litmus paper will turn blue.

Key Concept Flip

What observation confirms the presence of ammonia (NH3) gas?

Answer Flip

Ammonia gas is alkaline. Therefore, if the gas is ammonia, it will turn damp red litmus paper blue.

Example: if damp red litmus paper is held in a test tube containing ammonia gas, the paper will change from red to blue.
Key Concept Flip

Give an example of a thermal decomposition reaction that produces a metal oxide.

Answer Flip

Heating calcium carbonate (CaCO3) decomposes it into calcium oxide (CaO) and carbon dioxide (CO2).

Definition Flip

Define a 'basic oxide' and provide an example.

Answer Flip

A basic oxide reacts with acids to form salts and water.

Example: Magnesium oxide (MgO) reacts with hydrochloric acid (HCl) to form magnesium chloride (MgCl2) and water (H2O).
Definition Flip

Define an 'acidic oxide' and provide an example.

Answer Flip

An acidic oxide reacts with bases to form salts and water.

Example: Sulfur dioxide (SO2) reacts with sodium hydroxide (NaOH) to form sodium sulfite (Na2SO3) and water (H2O).
Key Concept Flip

What type of oxide is produced when a nonmetal reacts with oxygen?

Answer Flip

Generally, nonmetals react with oxygen to form acidic oxides.

Example: sulfur reacts with oxygen to form sulfur dioxide (SO2), which is an acidic oxide.
Key Concept Flip

What type of oxide is produced when a metal reacts with oxygen?

Answer Flip

Generally, metals react with oxygen to form basic oxides.

Example: magnesium reacts with oxygen to form magnesium oxide (MgO), which is a basic oxide.

Test yourself

Practice with MCQ questions to check your understanding.

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7.3 Preparation of salts 8.1 Arrangement of elements

Key Questions: Oxides

Define a 'basic oxide' and provide an example.

A basic oxide reacts with acids to form salts and water.

Example: Magnesium oxide (MgO) reacts with hydrochloric acid (HCl) to form magnesium chloride (MgCl2) and water (H2O).
Define an 'acidic oxide' and provide an example.

An acidic oxide reacts with bases to form salts and water.

Example: Sulfur dioxide (SO2) reacts with sodium hydroxide (NaOH) to form sodium sulfite (Na2SO3) and water (H2O).

Tips to avoid common mistakes in Oxides

More topics in Unit 7 — Acids, bases and salts

Oxides sits alongside these Chemistry decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.

7.1 Acids and bases

19 flashcards
7.2 Reactions of acids

10 flashcards
7.3 Preparation of salts

12 flashcards

Cambridge syllabus keywords to use in your answers

These are the official Cambridge 0620 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.

oxide acidic oxide basic oxide amphoteric oxide neutral oxide metal oxide non-metal oxide carbon dioxide sulfur dioxide calcium oxide aluminium oxide

Key terms covered in this Oxides deck

Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.

A 'basic oxide' and provide an example
An 'acidic oxide' and provide an example

Related Chemistry guides

Long-read articles that go beyond the deck — cover the whole subject's common mistakes, high-yield content and revision pacing.

IGCSE Chemistry MCQ mistakes

Single-letter mistakes most often costing marks in Paper 1/2

IGCSE Chemistry high-yield questions

Structured-question prompts that recur year after year

IGCSE Chemistry 2-week revision plan

Topic-by-topic plan for the 14 days before exams

How to study this Oxides deck

Start in Study Mode, attempt each card before flipping, then rate Hard, Okay or Easy. Cards you rate Hard come back within a day; cards you rate Easy push out to weeks. Your progress is saved in your browser, so come back daily for 5–10 minute reviews until every card reads Mastered.