Which of the following is not a common component of photochemical smog?

Complete reaction of acid rain is

$2S{O}_2+O_2+2H_{2}O\stackrel{}{\to }2H_{2}S{O}_4\left(acidrain\right)$  

BOD value less than 5ppm is considered as clean water and BOD value more than 10ppm is considered as polluted water.

BOD is the amount of oxygen required by bacteria to break down the organic matter present in a certain volume of sample of water.

Veronal is a barbiturate drug and it constitutes an important class of tranquilizers.

It is process in which nutrient enriched water bodies support a dense plant population which kills animal life by depriving it of oxygen and result in subsequent loss of biodiversity is known as Eutrophication.