Acid rain
(a) Causes necrosis
(b) Convert chlorophyll-a into pheophytin
(c) Responsible for the formation of PAN

Options

A. Only (a) and (b) are correct
B. Only (b) and ( c) are correct
C. Only (a) is correct
D. Only (c) is correct

Answer

To solve the question regarding acid rain and its effects, we will analyze each statement provided in the question step by step.

### Step 1: Understanding Acid Rain
Acid rain is formed when sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) are released into the atmosphere. These pollutants can combine with water vapor in the atmosphere to form sulfuric and nitric acids, which then fall to the ground as acid rain.

**Hint:** Remember that acid rain is primarily caused by pollutants like sulfur dioxide and nitrogen oxides.

### Step 2: Analyzing Statement (a) - Causes Necrosis
Necrosis refers to the premature death of plant cells or tissues. Acid rain can lead to necrosis in plants by damaging their leaves and stems, causing them to die off prematurely. This is due to the acidic nature of the rain, which can harm the plant's cellular structures.

**Hint:** Necrosis is related to the damage caused to plant tissues, especially leaves and stems.

### Step 3: Analyzing Statement (b) - Converts Chlorophyll-a into Pheophytin
Chlorophyll-a is the green pigment in plants that is essential for photosynthesis. Acid rain can cause the breakdown of chlorophyll-a into pheophytin, which is a non-photosynthetic pigment. This conversion reduces the plant's ability to perform photosynthesis, thus affecting its growth and health.

**Hint:** Chlorophyll breakdown leads to reduced photosynthesis, which is crucial for plant survival.

### Step 4: Analyzing Statement (c) - Responsible for the Formation of PAN
PAN stands for Peroxyacetyl Nitrate, which is a secondary pollutant formed from the reaction of volatile organic compounds (VOCs) and nitrogen oxides in the presence of sunlight. Acid rain itself does not directly cause the formation of PAN; therefore, this statement is incorrect.

**Hint:** PAN is a secondary pollutant and is not directly linked to acid rain.

### Conclusion
Based on the analysis:
- Statement (a) is correct: Acid rain causes necrosis.
- Statement (b) is correct: Acid rain converts chlorophyll-a into pheophytin.
- Statement (c) is incorrect: Acid rain is not responsible for the formation of PAN.

Thus, the correct answer is that only the first two statements (a and b) are correct.

**Final Answer:** (a) and (b) are correct; (c) is incorrect.