The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is about________?
A1.0 to 5.0 ppm
B0.05 to 0.5 ppm
C0.01 to 0.05 ppm
D0.5 to 1.0 ppm
Correct answer
B. 0.05 to 0.5 ppm
Explanation
The correct answer is 0.05 to 0.5 ppm.