Pollutants are the substances which present in the environment in greater proportion than its natural abundance and resulting in harmful or deterimental effect on the quality of environment. Generally highly toxic substances are considered . Generally highly toxic even substances that are normally considered harmless can cause pollution if they are present in underirable concentration. Over exploitation of natural resourses uncontrolled mechanisation deforestation and extensive use of chemical fertilizers and pesticides have brought about many changes in different component of the environment .
Acid rain is due to the increase in the concentration of . . . . . . . in the atmospheres

Options

A. `O_(3)`
B. `CH_(4)`
C. `SO_(2)` and `NO_(2)`
D. `O_(2)` and `CO`

Answer

**Step-by-Step Solution:**

1. **Understanding Pollutants**: Begin by recognizing that pollutants are substances that are present in the environment at higher levels than their natural abundance, leading to harmful effects. This includes both toxic substances and those that are harmless in low concentrations but become harmful at higher concentrations.

2. **Identifying Causes of Environmental Changes**: Acknowledge the factors contributing to environmental changes, such as over-exploitation of natural resources, deforestation, uncontrolled mechanization, and extensive use of chemical fertilizers and pesticides.

3. **Defining Acid Rain**: Define acid rain as precipitation that has a lower pH than normal rainwater, which is typically neutral (pH 7). Acid rain can harm ecosystems, buildings, and human health.

4. **Identifying the Gases Responsible for Acid Rain**: Recognize that acid rain is primarily caused by the presence of certain gases in the atmosphere. The two main gases responsible for acid rain are sulfur dioxide (SO₂) and nitrogen oxides (NO₂).

5. **Chemical Reactions Involved**: Understand the chemical reactions that lead to acid rain:
- When sulfur dioxide (SO₂) and nitrogen oxides (NO₂) are released into the atmosphere, they can react with water (H₂O) and oxygen (O₂) to form sulfuric acid (H₂SO₄) and nitric acid (HNO₃).
- The overall reactions can be summarized as:
- SO₂ + H₂O + O₂ → H₂SO₄ (sulfuric acid)
- NO₂ + H₂O → HNO₃ (nitric acid)

6. **Conclusion**: Conclude that the increase in the concentration of sulfur dioxide (SO₂) and nitrogen oxides (NO₂) in the atmosphere is what leads to the formation of acid rain.

**Final Answer**: Acid rain is due to the increase in the concentration of sulfur dioxide (SO₂) and nitrogen oxides (NO₂) in the atmosphere.

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