The main pollutant from automobile exhaust is

Photochemical smog is formed by .....

Ultraviolet radiation is absorbed by

Excessive release of $CO_2$ into the atmosphere results in

Which of the following practices will not come under green chemistry?
$1$. Using soaps made of vegetable oils instead of synthetic detergents,whenever possible.
$2$. Using $H_2O$ for bleaching purposes instead of chlorine-based bleaching agents.
$3$. Using liquefied $CO_2$ for dry cleaning clothes and laundry.
$4$. Using plastic cans for neatly storing substances.

Reducing smog is a mixture of