# A city plans to replace its fleet of diesel buses with buses powered by hydrogen-oxygen fuel cells. Explain why this change would reduce the environmental impact of the city's public transport system.

> Cambridge International IGCSE Chemistry (0620) — 4.2 Hydrogen-oxygen fuel cells · Explain · 4 marks

## Mark scheme (4 marks)

1. Hydrogen-oxygen fuel cells produce only water as a product / no harmful emissions from the fuel cell
2. Diesel combustion produces carbon dioxide / CO2, which is a greenhouse gas contributing to climate change / global warming
3. Diesel combustion produces pollutants such as sulfur dioxide / nitrogen oxides / particulates / soot / carbon monoxide, which harm air quality / health
4. Fuel cells are more efficient than diesel engines / less fuel is wasted as heat, so less fuel is needed for the same journey, reducing overall resource use / emissions

## Key terms

- [hydrogen-oxygen fuel cell](https://www.gradenine.co.uk/glossary/hydrogen-oxygen-fuel-cell)

## Related

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

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-city-plans-to-replace-its-72419a67) · Published by Druglandscape Ltd.