In context with the effectiveness of chlorine as a water disinfectant, choose the correct sequence in the descending order (i.e. 'from the most effective to the least effective')
- ABacteria, Viruses, ProtozoaCorrect
- BBacteria, Protozoa, Viruses
- CProtozoa, Viruses, Bacteria
- DViruses, Bacteria, Protozoa.
Solution
Concept
Chlorine effectiveness
Step-by-step solution
1. Chlorine is most effective against bacteria, less against viruses, and least against protozoan cysts.
Explanation
Cysts are very resistant to chlorine.
Why the other options are wrong
Other orders misplace the groups.
Shortcut
Bacteria > viruses > protozoa.
Correct answer: A) Bacteria, Viruses, Protozoa