Question 11 : The value of Reynolds number R is 1.5. The coefficient of drag is
1. 8
2. 10
3. 12
4. 16
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Question 12 : Identify the correct statement from the following options.
1. Rapid sand filter has a high initial cost
2. Coagulation is essential in slow sand filter
3. Slow sand filter requires skilled supervision
4. Period of cleaning of Rapid sand filter is 1-2 days
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Question 13 : In the ________ zone of purification in filter media, bacteria oxidizes the organic matter completely.
1. Autotrophic
2. Heterotrophic
3. Schmutzdecke
4. Electrolytic
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Question 14 : Which of the following order is correct regarding the specific gravity of the materials used in the mixed media filter?
1. Anthracite coal < Sand > Garnet sand
2. Anthracite coal > Sand > Garnet sand
3. Anthracite coal = Sand = Garnet sand
4. Anthracite coal < Sand < Garnet sand
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Question 15 : How the performance of rapid sand filter can be improved?
1. Replacing the top 15 cm layer of sand with Anthracite
2. Replacing the bottom15 cm layer of sand with Anthracite
3. Increasing the thickness of a layer of sand
4. Replacing 15 cm layer of Anthracite with sand
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Question 16 : Which is the first zone of purification in a sand bed?
1. Autotrophic zone
2. Heterotrophic zone
3. Schmutzdecke zone
4. Electrolytic zone
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Question 17 : Consider the following statement
1. The slow sand filter is not efficient in removing turbidity
2. The slow sand filter has a high initial cost
3. Skilled supervision is required in slow sand filter
Which of the above statement is/are correct?
1. Only 3
2. 1, 2
3. 1, 2, 3
4. 2, 3
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Question 18 : The depth of an enclosed tank of a rapid sand filter lies in the range of ______
1. 1-2m
2. 2.5-3.5m
3. 2-5m
4. 3-5m
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Question 19 : What is the size of sand used in a dual media filter?
1. 0.5-1mm
2. 1-2mm
3. 2-3mm
4. 3.5-4mm
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Question 20 : The effective size of sand of the slow sand filter is
1. 0.1-0.2mm
2. 0.2-0.3mm
3. 0.4-0.7mm
4. 1-2mm
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