Air pollutants are harmful to living things. Which of the following is/are their harmful effect(s)?
(i)They can form acid rain.
(ii)They cause breathing problems in humans.
(iii)They interfere with photosynthesis in plants.
(iv) They result in the depletion of ozone layer.

Options

A. (i) only
B. (i) and (ii) only
C. (i), (ii) and (iii) only
D. (i), (ii), (ii) and (iv)

Answer

To answer the question regarding the harmful effects of air pollutants, we will analyze each of the given statements one by one.

### Step-by-Step Solution:

1. **Identify the Effects of Air Pollutants**:
- We need to evaluate each of the four statements provided in the question to determine if they are indeed harmful effects of air pollutants.

2. **Evaluate Statement (i)**:
- **"They can form acid rain."**
- Air pollutants such as sulfur dioxide (SO2), carbon dioxide (CO2), and nitrogen oxides (NO2) can react with moisture in the atmosphere to form acid rain. This is a well-documented effect of air pollution.
- **Conclusion**: This statement is true.

3. **Evaluate Statement (ii)**:
- **"They cause breathing problems in humans."**
- Air pollutants are known to cause various respiratory issues, including chronic obstructive pulmonary disease (COPD) and asthma. Pollutants from vehicles and industries contribute significantly to these health problems.
- **Conclusion**: This statement is true.

4. **Evaluate Statement (iii)**:
- **"They interfere with photosynthesis in plants."**
- Air pollutants can negatively affect plants by reducing their ability to photosynthesize. This can lead to yellowing of leaves and reduced growth due to the harmful effects of pollutants on plant health.
- **Conclusion**: This statement is true.

5. **Evaluate Statement (iv)**:
- **"They result in the depletion of ozone layer."**
- Certain air pollutants, particularly chlorofluorocarbons (CFCs), are known to deplete the ozone layer. The ozone layer protects the Earth from harmful ultraviolet (UV) radiation, and its depletion poses serious environmental risks.
- **Conclusion**: This statement is true.

6. **Final Conclusion**:
- Since all four statements (i, ii, iii, and iv) are true, we can conclude that air pollutants have harmful effects as described in all the statements.

### Final Answer:
All of the following are harmful effects of air pollutants: (i) They can form acid rain, (ii) They cause breathing problems in humans, (iii) They interfere with photosynthesis in plants, and (iv) They result in the depletion of the ozone layer. Therefore, the correct answer is **1, 2, 3, 4**.

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