Molecular Theory & Factors
Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Clothes containing oil or 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.
Show answer and solution
Answer: (a)
- Water does not wet oil or grease: the angle of contact between them is obtuse.
- So water cannot spread over and lift the grease; detergent is needed to lower the angle of contact.
- (A) and (R) are both true and (R) explains (A). So the answer is (a).