Oxides of nitrogen combine to form

Options

(a) photochemical smog
(b) ozone
(c) smoke
(d) particulate matter

Correct Answer:

photochemical smog

Explanation:

Photochemical smog is grey or yellow brown opaque smog having oxidising environment with little smoke. Photochemical smog contains secondary pollutants or photochemical oxidants. It was first reported over Loss Angels in 1940s. Photochemical smog is formed at high temperature over cities and towns due to still air, emission of nitrogen oxides and carbohydrates from auto mobile exhausts and solar energy. Nitrogen dioxides splits into nitric oxide and nascent oxygen. Nascent oxygen combines with molecular oxygen to form ozone. Ozone reacts with carbohydrates to form aldehydes and ketones. Nitrogen oxides, oxygen and ketones combine to form peroxy-acyl-nitrates (PAN). In areas with intense solar radiations, photoelectrical smog forms brown air.