What is acid rain? State the pH value below which rain is classified as acid rain and explain one harmful eff…

Question

What is acid rain? State the pH value below which rain is classified as acid rain and explain one harmful effect it has on aquatic ecosystems.

Accepted Answer

## Model Answer Acid rain is rain water having pH less than **5.6**, caused by the presence of acidic pollutants like SO₂ and NO₂ dissolved in rainwater. **Harmful effect on aquatic ecosystems:** When acid rain flows into rivers, it lowers the pH of river water, making survival of aquatic life difficult. *Source: Chapter 2, Section 2.3.1 — Importance of pH in Everyday Life* --- ## Explanation - The examiner expects the **exact pH value of 5.6** — writing "less than 7" will not fetch marks. - One clearly stated harmful effect is enough for a 2-mark answer; do not over-explain. - The phrase "survival of aquatic life becomes difficult" directly mirrors the textbook language — using it shows the examiner you know the source material.

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