Oil and grease present in an emulsified state in waste water discharged from industries can be removed by
A. Biological oxidation
B. Skimming off
C. Settling out using chemical reagents
D. Chlorination
Answer: Option C
A. Biological oxidation
B. Skimming off
C. Settling out using chemical reagents
D. Chlorination
Answer: Option C
Fluorosis is caused due to the presence of excessive amount of __________ in drinking water.
A. Mercury
B. Lead
C. Fluoride
D. Arsenic
Smog is not formed due to the presence of __________ in the atmosphere.
A. SO2
B. NOx
C. CO2
D. Any of these
Dose of chlorine for disinfection of water is about __________ mg/litre of water.
A. 0.01
B. 0.1
C. 0.3
D. 1
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