Question 21 : As far as safer handling is considered, which of the following is used for fluoridation?
1. Sodium fluoride
2. Sodium silico fluoride
3. Hydrofluosilicic acid
4. Sodium fluro carbonate
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Question 22 : What concentration of iron and manganese will cause unpleasant taste and odor of water?
1. 1ppm
2. 2ppm
3. 3ppm
4. >3ppm
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Question 23 : State whether the following statement is true or false.
The pressure freezing process works on the vacuum free vapor compression principle.
1. True
2. False
3.
4.
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Question 24 : Which material is used for removing fluorides from hard water containing 3ppm of fluorides?
1. Lime
2. Copper sulfate
3. Synthetic tri-calcium phosphate
4. Bone charcoal
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Question 25 : In Electro-dialysis, the electric energy which required is
1. Directly proportional to cation permeable membrane
2. Directly proportional to anion permeable membrane
3. Directly proportional to salt concentration
4. Inversely proportional to salt concentration
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Question 26 : Which material is used in contact filters for removal of fluorides?
1. Calcium phosphate
2. Copper sulfate
3. Synthetic tri-calcium phosphate
4. Bone charcoal
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Question 27 : Multistage flash evaporator produces _____ kg of water per kg of prime steam.
1. 5
2. 10
3. 15
4. 20
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Question 28 : Which of the following is used for the control of taste and odor in water?
1. Sedimentation
2. Coagulation
3. Filtration
4. Activated carbon
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Question 29 : Which of the following regarding ozonation is incorrect?
1. Improves the appearance of water
2. Removes traces of color
3. Remove odor
4. Remove phenolic and algae taste
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Question 30 : At which temperature, the bone is calcinated during defluoridation with calcium phosphate?
1. 100-200^oC
2. 200-300^oC
3. 400-600^oC
4. 500-800^oC
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