(a) Ca

(b) Ba

(c) Fe

(d) Mg

(a) oxides of nitrogen are unstable

(b) catalyst is required for the reaction

(c) the reaction is endothermic

(d) N2 and O2 do not react with each other

(a) BOD value of clean water is less than 5 ppm

(b) Drinking water pH should be between 5.5-9.5

(c) carbon, sulphur and nitrogen oxides are the most widespread air pollutants

(d) dissolved oxygen concentration below 5 ppm is ideal for the growth of fish

(a) PAN

(b) N2O

(c) SO2

(d) CO2

(a) nuclear fission

(b) nuclear fusion

(c) chemical reaction

(d) combustion

(a) softens hard water

(b) pathogenic bacteria get destroyed

(c) impurities’ coagulation

(d) it improves taste

(a) Troposphere

(b) Thermosphere

(c) Stratosphere

(d) Mesosphere

(a) N2O5

(b) N2O

(c) NO

(d) NO2

(a) Chlorofluorocarbons

(b) Peroxyacetyl nitrate

(c) Ozone

(d) Acrolein

(a) Ferrocene

(b) Fullerenes

(c) Freons

(d) Polyhalogens