Question 61 : What is the settling velocity of the particle if its diameter is 2 * 10^-3cm. Given G=2.65, viscosity v=8 * 10^-3cm²/Sec?
1. 0.01cm/Sec
2. 0.13cm/Sec
3. 0.24cm/Sec
4. 0.36cm/Sec
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Question 62 : What will be the surface area of the basin for a flow of 2*106 litre per day having a surface loading rate 10,000 litre/day/m²?
1. 100
2. 200
3. 300
4. 400
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Question 63 : What is formed when coagulant is added to water?
1. Scum
2. Soap
3. Bubbles
4. Floc
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Question 64 : Ferric chloride is effective over a pH range of
1. 3.5-6
2. 6.5-8
3. 3.5-6.5
4. 2-5
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Question 65 : Why Alum is preferred over other coagulants?
1. It is easy to dewater the sludge formed
2. It imparts corrosiveness to water
3. It reduces taste and odor in addition to turbidity
4. The time required for floc formation is less
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Question 66 : In a rectangular horizontal flow tank, the maximum permissible velocity is ____ m/Sec.
1. 3
2. 0.3
3. 0.03
4. 0.003
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Question 67 : 1cm per second settling velocity corresponds to a surface loading of ______ litre per day per m²
1. 36000
2. 864000
3. 24000
4. 6000
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Question 68 : The design value of the velocity of flow in a flocculator is _______
1. 0.2-0.8m/s
2. 0.3-0.5m/s
3. 0.6-0.8m/s
4. 0.1-0.5m/s
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Question 69 : In which device, the primary mixing is followed by a secondary reaction zone resulting in formation of sludge blanket?
1. Centrifugal pump
2. Flocculator
3. Tube settler
4. Solid contact clarifier
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Question 70 : The quantity of water flowing per hour per unit horizontal area is called ____
1. Detention time
2. Flowing through period
3. Displacement time
4. Overflow rate
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