# Describe how you would use universal indicator solution to distinguish between a dilute acid, a neutral solution, and an alkali. Include the colours you would expect to observe.

> Cambridge International IGCSE Chemistry (0620) — 7.1 The characteristic properties of acids and bases · Describe · 4 marks

## Mark scheme (4 marks)

1. Add universal indicator solution to each sample / to the solution being tested
2. Dilute acid turns universal indicator red / orange (pH below 7)
3. Neutral solution turns universal indicator green (pH 7)
4. Alkali turns universal indicator blue / purple / violet (pH above 7)

## Key terms

- [universal indicator](https://www.gradenine.co.uk/glossary/universal-indicator)
- [acid](https://www.gradenine.co.uk/glossary/acid)
- [neutral](https://www.gradenine.co.uk/glossary/neutral)
- [alkali](https://www.gradenine.co.uk/glossary/alkali)

## Related

- [Revision notes for Cambridge International IGCSE Chemistry (0620)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-you-would-use-universal-2c06d8d7) · Published by Druglandscape Ltd.