Pollution by sulfur dioxide causes:

## The reasoning Sulfur dioxide (SO₂) is a gas released when we burn fossil fuels (coal, petrol, diesel) or during industrial processes. When SO₂ rises into the atmosphere, it **reacts with water vapor and oxygen** to form sulfuric acid (H₂SO₄): SO₂ + H₂O + O₂ → H₂SO₄ This sulfuric acid then falls back to Earth mixed with rain — that's **acid rain**. The principle here is **chemical transformation in the atmosphere**. Acid rain damages buildings, kills aquatic life, and harms crops. ## Why the wrong options tempt you **B) Floods** — You might confuse "rain" with flooding, but acid rain refers to the *acidity* of precipitation, not its quantity. **C) Drought** — Some pollutants affect weather, so you could guess drought, but SO₂ specifically creates acidic compounds, not dry conditions. **D) Earthquakes** — Physical events like earthquakes have nothing to do with atmospheric chemistry; they're caused by tectonic plate movements underground. ## Quick takeaway **Sulfur dioxide + water in the air = acid rain.** Remember: SO₂ changes rain's *chemistry*, not Earth's physical events.