Question

What is the main source of photochemical smog?

1) natural gas power plants
2) factories
3) automobiles
4) coal-burning power plants

Answer 1

3. Automobiles are the main source of photochemical smog due to the emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs).

Step-by-step explanation:

The main source of photochemical smog is 3. automobiles. When vehicles burn fuel, they emit nitrogen oxides (NOx) and volatile organic compounds (VOCs). Under sunlight, these pollutants react to form smog, which is a mixture of harmful chemicals that create a brown haze above cities.

Photochemical smog is a serious problem in many cities and can have negative effects on human health.