The amount of good quality bleaching powder required for chlorinating a round well measuring 4 mtrs diameter and depth of water column 6 mts, to get PPM of residual chlorine when the Horrok’stest gives definite blue colour in the 3rd cup onwards, is ?
Correct Answer: 993.8 grams
Description: Ans. is 'a' i.e., 993.8 grams o First we will have to find the volume of water in the well. o Now you must know how to calculate the amount of bleaching powder required to disinfect the well. o In Horrock's apparatus, 6 cups are filled with water and indicator (starch iodine) is added in increasing quantity in each cup (1 unit in 1st, 2 units in 2nd, 3 units in Ihird and so on). o The first cup which shows the blue color is multiplied by 2, for example if 2nd cup shows blue colour than 4 grams (2 x 2) of bleaching powder will required to disinfect 455 litre of water. o In the question 3rd cup is showing blue color. So, 6 gms (3 x 2) of bleaching powder will be required to disinfect 455 litre of water.
Category:
Social & Preventive Medicine
Get More
Subject Mock Tests
Practice with over 200,000 questions from various medical subjects and improve your knowledge.
Attempt a mock test nowMock Exam
Take an exam with 100 random questions selected from all subjects to test your knowledge.
Coming SoonGet More
Subject Mock Tests
Try practicing mock tests with over 200,000 questions from various medical subjects.
Attempt a mock test now