Assertion (A): Clothes containing oil grease stains cannot be cleaned by water wash.Reason (R): Because the angle of contact between the oil/grease and water is obtuse.In the light of the above statements, choose the correct answer from the option given below.
Question
Assertion (A): Clothes containing oil grease stains cannot be cleaned by water wash.Reason (R): Because the angle of contact between the oil/grease and water is obtuse.In the light of the above statements, choose the correct answer from the option given below.
Solution
The assertion (A) and the reason (R) are both correct and the reason (R) is the correct explanation for the assertion (A).
Here's why:
(A) Clothes containing oil or grease stains cannot be cleaned by water wash. This is true because oil and grease are hydrophobic substances, which means they repel water.
(R) The angle of contact between the oil/grease and water is obtuse. This is also true. The angle of contact is a measure of the wettability of a solid by a liquid. For hydrophobic substances like oil or grease, the angle of contact with water is more than 90 degrees (i.e., obtuse), which means water does not spread over the substance and cannot clean it effectively.
Therefore, the reason (R) correctly explains why the assertion (A) is true.
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