Science — AI-generated practice question

Acid rain is the rain water which has a pH less than 5.6. When oxides of nitrogen and sulphur (released by burning of fossil fuels) dissolve in rain water, they form nitric acid and sulphuric acid, making the rain acidic. Rain water with pH less than 5.6 is called acid rain.

Source: Chapter 2, Section 2.3.1

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• The definition must include two parts: what causes it (acidic gases dissolving in rain) and the pH value (< 5.6) — each part carries 1 mark.
• Examiners specifically look for the pH threshold of 5.6; writing "less than 7" will not earn the mark.
• Mentioning SO₂/NO₂ from fossil fuels adds accuracy but the pH value is the critical fact for the second mark.