Which group correctly represent the photochemical smog produced during reaction of hydrocarbon in the combustion chamber of an engine?

Options

A. Formaldehyde and PAN
B. Acrolein and PAN
C. Formaldehyde and acrolein
D. Formaldehyde, acrolein and PAN

Answer

To determine which group correctly represents the photochemical smog produced during the reaction of hydrocarbons in the combustion chamber of an engine, we can follow these steps:

### Step 1: Understand the Components of Photochemical Smog
Photochemical smog is primarily formed from the reaction of sunlight with pollutants such as nitrogen oxides (NOx) and unburned hydrocarbons.

### Step 2: Identify the Pollutants
When fossil fuels are burned, they release various pollutants, including:
- Nitric Oxide (NO)
- Unburned Hydrocarbons (HC)

### Step 3: Reaction of Pollutants with Sunlight
Nitric oxide (NO) reacts with sunlight to form nitrogen dioxide (NO2). The reaction can be summarized as:
\[ \text{NO} + \text{Sunlight} \rightarrow \text{NO}_2 \]

### Step 4: Formation of Ozone
Nitrogen dioxide (NO2) can further react with sunlight to produce ozone (O3) and free oxygen (O):
\[ \text{NO}_2 + \text{Sunlight} \rightarrow \text{NO} + \text{O} \]
\[ \text{O} + \text{O}_2 \rightarrow \text{O}_3 \]

### Step 5: Formation of Secondary Pollutants
The ozone (O3) produced is highly reactive and can react with unburned hydrocarbons to form secondary pollutants, including:
- Formaldehyde (HCHO)
- Acrolein (C3H4O)
- Peroxyacetyl Nitrate (PAN, C2H3NO4)

### Step 6: Conclusion
The correct group representing the photochemical smog produced during the reaction of hydrocarbons in the combustion chamber of an engine includes:
- Formaldehyde (HCHO)
- Acrolein (C3H4O)
- Peroxyacetyl Nitrate (PAN, C2H3NO4)

Thus, the correct answer is option number 4, which includes these compounds.

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