The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is about______________?

Related Mcqs:

1. Residual chlorine in water is determined by________________?

   A. starch iodide method
   B. orthotolidine method
   C. both (A) and (B)
   D. none of the above

2. The percentage of filtered water, which is used for backwashing in rapid sand filters, is about______________?

   A. 0.2 to 0.4
   B. 0.4 to 1.0
   C. 2 to 4
   D. 5 to 7

3. Chlorine demand of water is equal to________________?

   A. applied chlorine
   B. residual chlorine
   C. sum of applied and residual chlorine
   D. difference of applied and residual chlorine

4. The phenolic compounds in public water supply should not be more than_______________?

   A. 0.1 ppm
   B. 0.01 ppm
   C. 0.001 ppm
   D. 0.0001 ppm

5. If the coliform bacteria is present in a sample of water, then the coliform test to be conducted is_____________?

   1) presumptive coliform test
   2) confirmed coliform test
   3) completed coliform test
   The correct answer is ?

   A. only (1)
   B. both (1) and (2)
   C. both (1) and (3)
   D. all (1), (2) and (3)

6. The percentage of chlorine in fresh bleaching powder is about________________?

   A. 10 to 15
   B. 20 to 25
   C. 30 to 35
   D. 40 to 50

7. The disinfection efficiency of chlorine increases by_______________?

   1) decreasing the time of contact
   2) decreasing the temperature of water
   3) increasing the temperature of water
   The correct answer is ?
   A. only (1)
   B. both (1) and (2)
   C. both (1) and (3)
   D. only (3)

8. Assertion A: Slow sand filters are more efficient in removal of bacteria than rapid sand filters. Reason R : The sand used in slow sand filters is finer than that in rapid sand filters. Select your answer based on the coding system given below?

   A. Both A and R are true and R is the correct explanation of A
   B. Both A and R are true but R is not the correct explanation of A
   C. A is true but R is false
   D. A is false but R is true

9. Facultative bacteria are able to work in________________?

   A. presence of oxygen only
   B. absence of oxygen only
   C. presence as well as in absence of oxygen
   D. presence of water

10. Most of the bacteria in sewage are______________?

    A. parasitic
    B. saprophytic
    C. pathogenic
    D. anaerobic