1. The maximum desirable limit Bureau of Indian Standards (BIS) of lead in the drinking water is

A. 0.05 mg/l
B. 0.09 mg/l
C. 0.1 mg/l
D. 1.0 mg/l

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2. Zeolite softening process removes

A. only temporary hardness of water
B. only permanent hardness of water
C. both temporary and permanent hardness of water
D. the dissolved gases in permanent hard water

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3. Conventional tertiary treatment is

A. chemical coagulation and flocculation
B. filtration
C. sedimentation
D. none of these

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4. The maximum desirable limit (BIS) of total hardness (as CaCo₃) in drinking water is

A. 600 ppm
B. 300 ppm
C. 500 ppm
D. 1000 ppm

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5. The chemical oxygen demand (COD)measures the

A. amount of oxygen required for growth of microorganisms in water
B. amount of oxygen that would be removed from the water in order to oxidize pollution
C. amount of oxygen required to oxidize the calcium present in wastewater
D. none of the above

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