Question

Photochemical smog formed in congested metropolitan cities mainly consists of

(a) ozone, peroxyacyl nitrate and NO₂

(b) smoke, peroxyacyl nitrate and SO2

(c) hydrocarbons, SO₂ and CO₂

(d) hydrocarbons, ozone and SO_x

Answer 1

Correct option (a) ozone, peroxyacyl nitrate and NO₂

Explanation :

Photochemical smog is a grey or yellowish brown opaque smog haling oxidizing environment but little smokes. It is formed at high temperature over cities and towns due to still air, emission of NO₂ oxides and hydrocarbons from automobile exhausts. Nitrogen dioxide splits into nitric oxide and nascent oxygen. Nascent oxygen combines with molecular oxygen to form ozone. Ozone reacts with hydrocarbons to form aldehydes and ketones. Nitrogen oxides, oxygen and ketones combine to form peroxy-acyl-nitrates (PAN).