Question

Assertion (A): The aggregate of carboxylate ions of fatty acids forms a spherical shape.
Reason (R): Soap helps in emulsification and washing away of oils.

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A).
• B. Both (A) and (R) are correct but (R) is not the correct explanation of (A).
• C. (A) is correct but (R) is incorrect.
• D. (A) is incorrect but (R) is correct.

Hint:

Soap molecules form micelles in water. The hydrophobic tails remain inside the micelle while the hydrophilic carboxylate heads remain outside. Micelle formation enables emulsification and cleansing action.

Answer 1

The Correct Option is B

Step 1: Analyze Assertion (A).
Soap molecules are sodium or potassium salts of long-chain fatty acids.
Each soap molecule contains: \[ \text{Hydrophilic head }(-COO^-) \] and Hydrophobic hydrocarbon tail In aqueous solution, these molecules aggregate to form spherical structures called micelles.
In a micelle, the hydrocarbon tails remain inside while the ionic carboxylate heads remain on the outside in contact with water.
Therefore, the aggregate of carboxylate ions of fatty acids forms a spherical micellar structure.
Hence, Assertion (A) is correct.

Step 2: Analyze Reason (R).
Soap helps in cleaning by emulsifying oils and grease.
The non-polar hydrocarbon tails dissolve in oil droplets, while the polar ionic heads remain in water.
As a result, oil gets surrounded by soap molecules and is dispersed in water as an emulsion, which can then be washed away.
Therefore, Reason (R) is also correct.

Step 3: Examine whether (R) explains (A).
Assertion (A) describes the formation of spherical micelles by soap molecules.
Reason (R) describes the cleansing action of soap due to emulsification.
Although emulsification occurs because micelles are formed, the statement about washing away oils does not directly explain why the aggregates themselves assume a spherical shape.
Thus, (R) is not the correct explanation of (A).

Step 4: Final conclusion.
Both Assertion (A) and Reason (R) are correct, but Reason (R) is not the correct explanation of Assertion (A).
Therefore, \[ \boxed{\text{Both (A) and (R) are correct but (R) is not the correct explanation of (A).}} \] Hence, the correct option is \[ \boxed{(2)} \]