Disinfection of Water MCQ – Environmental Engineering

21. For disinfection of water with uluraviolet rays, the turbidity should not exceed

  1. 25 mg/l
  2. 15 mg/
  3. 75 mg/l
  4. 50 mg/l
Answer
Answer. b

22. Which one of the following chemicals is employed for dechlorination of water?

  1. Sodium sulphite
  2. Sodium bicarbonate
  3. Calcium carbonate
  4. Hydrogen peroxide
Answer
Answer. a

23. In chlorination, due to rise in temperature of water, death rate of bacteria

  1. increases
  2. decreases
  3. remains unaffected
  4. none of the above
Answer
Answer. a

24. Residual chlorine in water is determined by

  1. starch iodide method
  2. orthotolidine method
  3. both a and b
  4. none of the above
Answer
Answer. c

25. Normal standard process of applying chlorine to water

  1. Plain chlorination
  2. Pre chlorination
  3. Post chlorination
  4. Double chlorination
Answer
Answer. c

26. In water Ureaunent both pre-, and post-, chlorination of water are done to control

  1. Colour
  2. Odour
  3. Water-borne diseases due to bacteria
  4. Algae
  5. Turbidity
  6. TDS

Which of the above are correct?

  1. i, ii, iii and iv
  2. ii, iii, iv and v
  3. iii, iv, v and vi
  4. i, iii, v and vi
Answer
Answer. a

27. Process which involves chlorination beyond the break point is known as

  1. Post-chlorination
  2. Pre-chlorination
  3. Hype-chlorination
  4. Super- chlorination
Answer
Answer. d
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