Question 11 : State whether the following statement is true or false.
Fluorides in solution form are preferred over powdered form for fluoridation.
1. True
2. False
3.
4.
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Question 12 : The fluoride concentration for prevention of dental caries is
1. 1mg/l
2. 2mg/l
3. 3mg/l
4. 4mg/l
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Question 13 : Which of the following is not a property of activated carbon?
1. It is impermeable
2. It has many carbon atoms with free valencies
3. It is available in granular as well as powder form
4. It has a prolonged suspension
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Question 14 : Removal of iron from water takes place at a pH of ______
1. 1.5
2. 3
3. 8.2
4. 9.4
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Question 15 : Which of the following method is not used for desalination?
1. Distillation
2. Coagulation
3. Reverse osmosis
4. Freezing
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Question 16 : _______ is produced by passing a carbonaceous material through a heating mechanism at high temperature.
1. Potassium per-manganate
2. Potassium dichromate
3. Activated carbon
4. Iodine
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Question 17 : The process of reducing the fluoride content from water is called _____
1. Chlorination
2. Fluoridation
3. Defluoridation
4. Flocculation
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Question 18 : For removal of manganese from water, ________ mg of oxygen is required.
1. 0.14
2. 0.50
3. 0.29
4. 0.90
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Question 19 : The solar evaporation can yield about ___ kg of fresh water per day per m² of basin surface.
1. 5
2. 10
3. 15
4. 20
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Question 20 : What happens when water contains 8-20 ppm of fluoride concentration?
1. Blue baby disease
2. Crippling fluorosis
3. Dental fluorosis
4. Mottling of teeth
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