$CF_xCly$ [where $x + y = 4$] compounds are not useful because .....

The presence of ozone in the troposphere:

When the biosphere becomes an environment useful to humans,what is it called?

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.

What are the harmful effects of photochemical smog and how can they be controlled?

In an agricultural field,which among the following is the highest producer of methane?