The brown color of photochemical smog is primarily due to which of the following?

Sulphur dioxide is one of the components of polluted air. $SO_{2}$ is also a major contributor to acid rain. The correct and complete reaction to represent acid rain caused by $SO_{2}$ is ..... .

Write a note on the effect of various pesticides on living things.

Indiscriminate use of $DDT$ is undesirable because

How do chlorofluorocarbons (CFCs) deplete the ozone layer in the stratosphere? Explain with the associated chemical reactions.

How can you apply Green Chemistry for the following?
$(a)$ To reduce photochemical smog.
$(b)$ To avoid the use of chlorinated solvents and chlorinated bleaching agents in dry cleaning.
$(c)$ To reduce the use of synthetic detergents.
$(d)$ To reduce the consumption of petrol and diesel.