Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Clothes are not washed properly in hard water.
Reason (R): Hard water contains many minerals.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Both (A) and (R) are correct but (R) is not the correct explanation of (A)
Assertion (A) — True. In hard water, soap does not lather well. The calcium and magnesium ions of the water react with soap (sodium salts of fatty acids) to form an insoluble scum of calcium and magnesium salts. Much of the soap is wasted this way, and the scum sticks to the cloth, so clothes are not washed properly.
Reason (R) — True. Hard water contains dissolved minerals: the bicarbonates, chlorides and sulphates of calcium and magnesium that it picks up while flowing over rocks and through the soil.
Does (R) explain (A)? As per the answer given by NTA, no. The Reason only says that hard water carries many minerals; it does not say what those minerals do to soap. Many dissolved minerals, such as sodium salts, do not harm the washing at all; the poor washing comes from the calcium and magnesium ions forming scum with the soap.
Note: One can argue that the minerals of hard water are the very calcium and magnesium salts that spoil the soap, so the Reason would explain the Assertion, which is Option (1). The answer given by NTA reads the Reason as too general, since it names no mineral and no reaction with soap.