Question

When soaps or detergent dissolves in water, which statement is true?
A. The polar water soluble (hydrophilic) head is on the surface of the micelle whereas non polar oil soluble (hydrophobic) tail is in the centre of the micelle.
B. The polar water soluble (hydrophilic) head is in the centre of the micelle whereas non polar oil soluble (hydrophobic) tail is on the surface of the micelle.
C. The polar water soluble (hydrophilic) head is in the centre of the molecule.
D. Non polar oil soluble (hydrophobic) tail is on the surface of the molecule.

Answer 1

A soap is defined as a water-soluble compound made by a process called saponification that can be done by the reaction between sodium hydroxide or potassium hydroxide with vegetable or animal oil known as fats. Whereas Amphipathic molecules which contain charged polar groups at the end of long lipophilic hydrocarbon groups are called detergents.

Complete answer:
When soaps and detergents dissolve in water then most of the dirt particles present are oily in nature and we know that oil does not dissolve in water. The molecule of soap constitutes sodium or potassium salts of long-chain carboxylic acids. When soaps dissolves in water then the carbon chain dissolves in oil and the ionic end dissolves in water and it forms micelles.
Micelle has two ends the first one is the hydrophilic end which dissolves water and is attracted to it whereas the second one is the hydrophobic end that is dissolved in hydrocarbons and is water repulsive in nature. If on the surface of the water, soap is present then the hydrophobic tail which is not soluble in water will align along the water surface.

Hence option A is the correct answer.

Note:
In micelles we can consider that one end is towards the oil droplet and the other end has the ionic faces in the outside face. Due to this it forms an emulsion in water which helps in dissolving the dirt when we wash our clothes.