Which of the following are essential requirements for the formation of photochemical smog? Choose the most appropriate answer from the options given below.

1.Carbon monoxide (CO)

2.Nitrogen dioxide (NO2)

3.Carbon dioxide (CO2)

4.Volatile Organic Compounds (VOCs)

5.Sunlight

A1, 2 and 4 only

B1, 3 and 5 only

C2, 3, 4 and 5 only

D2, 4 and 5 only ✓ Correct

Correct answer: (D) 2, 4 and 5 only

Explanation

Photochemical smog forms when nitrogen dioxide and volatile organic compounds react in strong sunlight.

Statement 1 is wrong: carbon monoxide is a pollutant but is not an essential ingredient of this smog.

Statement 2 is right: nitrogen dioxide is a key precursor that begins the reaction chain.

Statement 3 is wrong: carbon dioxide plays no essential role in forming photochemical smog.

Statement 4 is right: volatile organic compounds supply the reactive carbon needed.

Statement 5 is right: sunlight drives the photochemical reactions that create the smog.

The chief product of this smog is ground-level ozone along with irritants like PAN.

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