JEE Main202229 Jul 2022Morning ShiftPhysicsMechanical Properties of FluidsActual
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.
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is true but (R) is true
Correct answer
A. Both (A) and (R) are true and (R) is the correct explanation of (A)
Step-by-step solution
Angle of contact between oil and water is obtuse i.e., greater than critical angle of contact θ c > 90 ° , therefore they do not stick and that's the reason grease/oil stains can not be removed by water wash. Thus, both (A) and (R) are true and (R) is the correct explanation of (A).