A sample of hard water is taken in two containers A and B. To container 'A ', a detergent is added and soap is added to container 'B'. The water in 'A' is more efficient in cleaning than the water in 'B' . Justify.

Explanation

Effectiveness of soap is reduced when used in hard water. Hardness in water is caused by the presence of mineral salts mostly of Ca and Mg. The mineral salt reacts with soap to form an insoluble precipitate known as scum. Lather formation is reduced. Detergent forms soluble compounds with calcium and magnesium and hence does not form scum with hard water. Due to this reason, water in 'A' is more efficient in cleaning than water in 'B'.