Question

The quantity of calgon to be added to prevent scale and sludge formation is ___________

(a) 10-20 ppm

(b) 30-50 ppm

(c) 0.005-0.1 ppm

(d) 0.5-5 ppm

The question was posed to me in an interview for internship.

This is a very interesting question from Calgon Conditioning in section Water and its Treatment of Engineering Chemistry II

Answer 1

Right option is (d) 0.5-5 ppm

The best explanation: The quantity of calgon to be added to prevent scale and sludge formation is 0.5-5 ppm. It is used in small quantity.