Which of the following group of gases cause photochemical smog?

Options

A. `O_3` ,PAN and CO
B. HC, NO and PAN
C. `O_2 , PAN and NO_2`
D. `O_3 `, PAN and `NO_2`

Answer

D

Explanation

Photochemical smog is formed in traffic congested cities where warm conditions and intense solar radiation are present. It has mainly `O_3` , PAN and `NO_2` . It is called brown air and grey air when solar radiation is intense and lesser respectively.