Which one of the following statements is not true

Options

A. Clean water would have a BOD value of 5 ppm
B. Fluoride deficiency in drinking water is harmful. Soluble fluoride is often used to bring its concentration upto 1 ppm
C. When the pH of rain water is higher than ,5.6 it is called acid rain
D. Dissolved Oxygen (DO) in cold water can reach a concentration upto 10 ppm

Answer

C

Explanation

When the pH of rain water is higher than ,5.6 it is called acid rain