# A student reacts calcium oxide with dilute hydrochloric acid and separately reacts calcium oxide with water. Describe what happens in each reaction and explain how these reactions show that calcium oxide is a basic oxide.

> Cambridge International IGCSE Chemistry (0620) — 7.2 Oxides · Describe and Explain · 4 marks

## Mark scheme (4 marks)

1. Calcium oxide reacts with dilute hydrochloric acid to form a salt (calcium chloride) and water
2. Calcium oxide reacts with water to form calcium hydroxide (an alkali / alkaline solution)
3. A basic oxide is one that reacts with acids to form a salt and water only (neutralisation)
4. Calcium oxide is a basic oxide because it reacts with acid (to neutralise it) but does not react with bases/alkalis

## Key terms

- [basic oxide](https://www.gradenine.co.uk/glossary/basic-oxide)

## Related

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- [How to answer "Describe and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-reacts-calcium-oxide-with-5942b0fe) · Published by Druglandscape Ltd.