Question

The number of bacterial colonies by Agar plate count test should not exceed ____ per ml for potable water.

(a) 1

(b) 10

(c) 100

(d) 1000

The question was asked in a national level competition.

My enquiry is from Biological Characteristic of Water topic in division Quality of Water of Environmental Engineering

Answer 1

The correct answer is (c) 100

For explanation I would say: Agar plate count test is a test to count the number of bacterial colonies growing on a specified medium and the permissible limit for the number of bacterial colonies is 100 per ml.