Clean water would have a BOD value of 5 ppm.

Fluoride deficiency in drinking water is harmful. Soluble fluoride is often used to bring its concentration upto 1 ppm.

When the pH of rain water is higher than 6.5, it is called acid rain.

Dissolved Oxygen (DO) in cold water can reach a concentration upto 10 ppm.

Carbon monoxide does not play any role in photochemical smog formation.

Photochemical smog is an oxidation agent in character.

Photochemical smof is formed through photochemical reaction involving solar energy.

Photochemical smog does not cause irritation in eyes and throat.

pH of drinking water should be between 5.5 $$-$$ 9.5

Concentration of DO below 6 ppm is good for the growth of fish.

Clean water would have a BOD value of less than 5 ppm.

Oxides of sulphur, nitrogen and carbon are the most widespread air pollutant.

are related to the depletion of ozone layer

study the reactions in plants

produce colour during reactions

reduce the use and production of hazardous chemicals.