# State two pollutant gases produced when petrol burns incompletely in a car engine, and for each gas, describe one harmful effect on either human health or the environment.

> Cambridge International IGCSE Chemistry (0620) — 10.3 Air quality and climate · State · 4 marks

## Mark scheme (4 marks)

1. Names carbon monoxide (CO) as a pollutant gas from incomplete combustion
2. Describes a harmful effect of carbon monoxide — reduces ability of blood/haemoglobin to carry oxygen, leading to reduced oxygen supply to the body / can cause death
3. Names nitrogen monoxide / nitrogen dioxide / nitrogen oxides (NOx) as a pollutant gas from incomplete combustion or high-temperature combustion
4. Describes a harmful effect of nitrogen oxides — causes acid rain which damages ecosystems / buildings / kills aquatic life, OR irritates the respiratory system / causes breathing problems

## Related

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