A. 10 to 15
B. 20 to 25
C. 30 to 35
D. 40 to 50
Related Mcqs:
- The treatment of water with bleaching powder is known as________________?
A. prechlorination
B. super chlorination
C. dechlorination
D. hypochlorination - Period of cleaning of slow sand filters is about________________?
A. 24 – 48 hours
B. 10-12 days
C. 2-3 months
D. 1-2 year - Residual chlorine in water is determined by________________?
A. starch iodide method
B. orthotolidine method
C. both (A) and (B)
D. none of the above - 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 - 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) - The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is about______________?
A. 0.01 to 0.05 ppm
B. 0.05 to 0.5 ppm
C. 0.5 to 1.0 ppm
D. 1.0 to 5.0 ppm - The characteristics of fresh and septic sewage respectively are____________________?
A. acidic and alkaline
B. alkaline and acidic
C. both acidic
D. both alkaline - Percentage of bacterial load that can be removed from water by the process of plain sedimentation is about_______________?
A. 10 to 25
B. 50
C. 75
D. 100 - 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 - Alum as a coagulant is found to be most effective when pH range of water is______________?
A. 2 to 4
B. 4 to 6
C. 6 to 8
D. 8 to 10
