Question

Photochemical smog formed in congested metropolitan cities mainly consists of

• A. Ozone, peroxyacetyl nitrate and NO${}_2$
• B. Smoke, peroxyacetyl nitrate and SO${}_2$
• C. Hydrocarbons, SO${}_2$ and CO${}_2$
• D. Hydrocarbons, ozone and SO${}_2$

Answer 1

Answer: (A)

Ozone, peroxyacetyl nitrate and NO${}_2$

• The chemicals in photochemical smog include nitrogen oxides, volatile organic compounds (VOCs), ozone, and PAN (peroxyacetyl nitrate). Nitrogen oxides mostly come from the engines of cars and trucks. VOCs are given off by paint, gasoline, and pesticides. Ozone is a form of oxygen that is harmful. PAN is a type of pollution that is made by chemical reactions between other kinds of pollution.
• Photochemical smog is a condition that develops when oxides of nitrogen and volatile organic compounds react in the presence of sunlight to produce a mixture of hazardous chemicals known as secondary pollutants. The mixture of these primary and secondary pollutants forms photochemical smog.

Thus, the correct answer is option A.