The formation of photochemical smog depends upon

Options

A. CO
B. NO
C. `CO_(2)`
D. `SO_(2)`

Answer

To solve the question regarding the formation of photochemical smog, we need to understand the components and conditions that contribute to its formation. Here’s a step-by-step breakdown:

### Step 1: Understand Photochemical Smog
Photochemical smog is a type of air pollution that occurs when sunlight reacts with pollutants in the atmosphere. It is characterized by a brown haze and is primarily composed of nitrogen oxides (NOx), ozone (O3), and peroxyacetyl nitrate (PAN).

**Hint:** Remember that photochemical smog is linked to sunlight and specific pollutants.

### Step 2: Identify Key Components
The main components involved in the formation of photochemical smog include:
- Nitrogen Dioxide (NO2)
- Ozone (O3)
- Peroxyacetyl Nitrate (PAN)

These substances are formed through chemical reactions driven by sunlight.

**Hint:** Focus on the specific gases that are produced and their reactions with sunlight.

### Step 3: Role of Nitrogen Dioxide
Nitrogen dioxide (NO2) plays a crucial role in the formation of photochemical smog. When exposed to sunlight, NO2 can break down into nitric oxide (NO) and nascent oxygen (O). This reaction is significant in the formation of ozone and other secondary pollutants.

**Hint:** Consider how nitrogen dioxide interacts with sunlight and what products are formed.

### Step 4: Identify the Correct Option
From the options provided (CO, NO, CO2, SO2), we need to identify which gas is relevant to the formation of photochemical smog. Since NO (nitric oxide) is produced from the breakdown of NO2 in the presence of sunlight, it is the correct answer.

**Hint:** Look for the gas that is directly involved in the reactions leading to photochemical smog.

### Conclusion
The formation of photochemical smog depends on the presence of nitrogen oxides, particularly nitrogen dioxide, which reacts with sunlight to produce nitric oxide (NO) and other pollutants. Therefore, the correct answer is **NO**.

### Final Answer
The formation of photochemical smog depends upon **NO (Nitric Oxide)**.

---