Water Supply Engineering

41. By adding 1 ml of Orthotolidine solution to 100 ml chlorinated water taken after contact period, the residual chlorine makes the colour of solution

1. Yellowish
2. Greenish
3. Bluish
4. Reddish

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42. By boiling water, hardness can be removed if it is due to

1. Calcium sulphate
2. Magnesium sulphate
3. Calcium nitrate
4. Calcium bicarbonate

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43. Capacity of soil to absorb moisture, is generally known as

1. Permeability
2. Porosity
3. Infiltration capacity
4. Perviousness

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44. Carbonates in water produce

1. Temporary hardness
2. Permanent hardness
3. Acidity
4. Alkanity

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45. Cast iron pipes

1. Are widely used in city water supplies
2. Resist corrosion satisfactorily
3. May last for 100 years
4. All the above

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46. Cast iron pipes are generally preferred to, because

1. Of moderate cost
2. Of ease to join
3. Of longer life
4. All the above

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47. Check valves are installed

1. On the delivery side of the pumping set
2. At the interconnections between polluted water system and a potable water system
3. Both (a) and (b)
4. Neither (a) nor (b)

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48. Chemical coagulation of drinking water, is done

1. To settle suspended materials
2. To increase rate of settlement of suspended materials
3. To remove the bacterias
4. None of these

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49. Chlorination of water does not remove

1. Ammonia content
2. B.O.D.
3. Organic matter content
4. Dissolved oxygen

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50. Continuous flow of water can be expected from

1. Gravity springs
2. Surface springs
3. Artesian springs
4. None of these

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