Question

Photochemical smog does not contain ________.

• A. PAN
• B. Ozone
• C. Nitrogen dioxide
• D. $S{O}_2$

Answer 1

The correct option is D $S{O}_2$

The photochemical reaction is caused by absorption of energy in the form of light. The word smog is formed of smoke and fog. Photochemical smog is the major contributor to air pollution and is composed of primary and secondary pollutants. Primary being the nitrogen oxides and volatile organic compounds. Unsaturated hydrocarbons are those that have double or triple covalent bonds between adjacent carbon atoms. e.g., Ethylene, Gasoline and natural gas are the major sources of unsaturated hydrocarbon. Butadiene, benzene are some hydrocarbons that are lethal to human health and have the potential to cause cancer. The emitted sulphur dioxide is oxidized in the troposphere thereby forming sulphuric acid which on mixing with water forms the component of acid rain.

Hence, the correct answer is 'SO${}_2$'.