8.  Zeolite used in zeolite softening process for the treatment of hard water gets exhausted after certain time of usage but can be regenerated by flushing it with
A.10% calcium chloride solution
B.10% magnesium sulfate solution
C.10% magnesium chloride solution
D.10% sodium chloride solution

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9. Temporary hardness of water is caused by the presence of
A.chlorides of calcium and magnesium
B.sulfates of calcium and magnesium
C.bicarbonates of calcium and magnesium
D.carbonates of sodium and potassium

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10. Secondary treatment uses __________ to consume wastes.
A.micro-organisms
B.chemicals
C.filtration
D.none of these

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11. Application of quaternary ammonium compounds as sanitizing agents tends to
A.favor gram positive bacteria
B.decrease gram positive bacteria
C.increase the percentage of gram(-)ve rods on utensils
D.none of the above

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12. Permanent hardness of water is caused by the presence of
A.bicarbonates of calcium and magnesium
B.carbonates of sodium and potassium
C.chlorides and sulfates of calcium and magnesium
D.phosphates of sodium and potassium

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13. According to BIS the maximum permissible limit of dissolved solids in drinking water is
A.1000 mg/l
B.500 mg/l
C.2000 mg/l
D.1500 mg/l

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14. Acid used mostly for removal of milk stone is
A.phosphoric acid
B.nitric acid
C.gluconic acid
D.tartaric acid

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