Water Quality MCQ – Environmental Engineering

1. Hardness is caused by

  1. all metallic ions
  2. divalent metallic ions
  3. sulphates and chlorides
  4. carbonates and bicarbonates
Answer
Answer. b

2. How the temporary hardnesss of water is removed?

  1. by lime soda process
  2. by boiling
  3. by zeolite process
  4. by aeration
Answer
Answer. b

3. Permanent hardness of water is due to the presence of

  1. bicarbonates of calcium and magnesium
  2. toxic materials
  3. sulphate and chlorides of calcium and magnesium
  4. metallic oxides
Answer
Answer. c

4. What is the method of removal of permanent hardness in water?

  1. Lime-soda process
  2. Zeolite process
  3. Reverse osmosis
  4. All of these
Answer
Answer. d

5. Zero hardness of water can be achieved by

  1. Lime soda process
  2. Excess lime treatment
  3. Ion exchange method
  4. Excess alum dosage
Answer
Answer. c

6. The hardness is expressed in degrees as per

  1. Clark’s scale
  2. Carbonate hardness
  3. Total hardness
  4. Non-carbonate hardness
Answer
Answer. a

7. Bicarbonates of calcium and magnesium cause

  1. Permanent hardness in water
  2. Temporary hardness in water
  3. Both permanent and temporary hardness in water
  4. No hardness in water
Answer
Answer. b

8. Hardness is expressed in mg/L as

  1. Ca(HCO3)2
  2. CaCO3
  3. Ca(OH)2
  4. CaSO4
Answer
Answer. b

9. Presence of chlorides and sulphates of calcium and magnesium in water causes

  1. Acidity
  2. Temporary hardness t0seaudhes
  3. Permanent hardness
  4. Softness
Answer
Answer. c

10. If the total hardness of a water sample from complete analysis is found to be 120 mg/L and the non-carbonate hardness is 50 mg/L. The carbonate (in mg/L) shall then be

  1. 170
  2. 70
  3. 20
  4. 2.4
Answer
Answer. b

11. A Compound that imparts temporary hardness to water

  1. Calcium sulphate
  2. Magnesium chloride
  3. Calcium nitrate
  4. Magnesium carbonate
Answer
Answer. d

12. If the total hardness and alkalinity of a sample of water are 300 mg/L and 100 mg/L (as CaCO3) respectively, then its carbonate and non-carbonate hardness will be respectively

  1. 100 mg/L and 200 mg/L
  2. 400 mg/L and 300 mg/L
  3. 100 mg/L and 400 mg/L
  4. 400 mg/L and 0 mg/L
Answer
Answer. a

13. Temporary hardness in water is caused by

  1. Carbonates and bicarbonates of calcium and magnesium
  2. Bicarbonates of sodium and potassium
  3. Carbonates of calcium and potassium
  4. Dissolved carbon dioxide
Answer
Answer. a

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

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

15. Permanent hardness is removed by

  1. Lime soda process
  2. Boiling
  3. Demineralization process
  4. Base exchange process
  1. ii only
  2. i only
  3. All of the above
  4. i, iii and iv
Answer
Answer. d

16. Hardness of water is caused by

  1. presence of soap lather
  2. presence of chlorides and sulphates of sodium and potassium
  3. presence of CO3, SO4 0r chlorides of calcium and Magnesium
  4. turbidity
Answer
Answer. c

17. The hardness of boiler feed water should not be more than about

  1. 5 mg/L
  2. 2 mg/L
  3. 20 mg/L
  4. 50 mg/L
Answer
Answer. d

18. If the total hardness of water is greater than its alkalinity, the carbonate hardness will be equal to

  1. non-carbonate hardness
  2. total hardness
  3. total hardness-total alkalinity
  4. total alkalinity
Answer
Answer. d

19. The presence of hardness in excess of permissible limit causes

  1. Cardio-vascular problems
  2. Skin discolouration
  3. Calcium deficiency
  4. Increased laundry expenses
Answer
Answer. d

20. Zero hardness of water is achieved by

  1. Using lime soda process
  2. Excess lime treatment
  3. Ion exchange method
  4. Using excess alum dosage
Answer
Answer. c
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