London smog is found in

Reducing smog is a mixture of

An increase in $CO_2$ concentration in the atmosphere will result in

When plants and animals decay,the organic nitrogen is converted into inorganic nitrogen. The inorganic nitrogen is in the form of

Methane in the polluted air reacts with oxygen to form which of the following compounds?

Photochemical smog consists of an excessive amount of $X$,in addition to aldehydes,ketones,peroxyacetyl nitrate $(PAN)$,and so forth. $X$ is