![Chlorine is used as the disinfectant in a municipal water treatment plant. It achieves 50 percent of disinfection](https://www.gkseries.com/blog/wp-content/uploads/2023/08/Chlorine-is-used-as-the-disinfectant-in-a-municipal-water-treatment-plant.-It-achieves-50-percent-of-disinfection.jpg)
Q. Chlorine is used as the disinfectant in a municipal water treatment plant. It achieves 50 percent of disinfection efficiency measured in terms of killing the indicator microorganisms (E-Coli) in 3 minutes. The minimum time required to achieve 99 percent disinfection efficiency would be
(A) 9.93 minutes
(B) 11.93 minutes
(C) 19.93 minutes
(D) 21.93 minutes
Ans: 19.93 minutes
Solution:
Disinfection efficiency
![](https://www.gkseries.com/blog/wp-content/uploads/2023/08/Screenshot-458-1.png)