Question

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

Answer 1

Hint: We must have to know that soaps and detergents are used as surfactants and for better cleaning of oil and grease dirt on the clothes. A micelle formation enables better cleaning of clothes. Soaps and detergents are effective in hard water and soft water, they are used in industries for heavy works and in households.

Complete answer:
We must know that when soap or detergent is added to the surface tension of water molecules decreases. Due to the decrease in surface tension the water molecules stick to the cloth or dirt. Hence, soap or detergent is added for the better cleaning of clothes. When soap or detergent is added, formation of micelle occurs. Micelle is formed by the hydrophobic and hydrophilic ends. An end that is water attracting or the polar end is called the hydrophilic end while the other is water repelling or the non polar end called hydrophobic end.
The hydrophobic end gets attached to the dirt on the cloth that may be oil, grease. While the hydrophilic end repels the oil or grease and remains on the other end. Due to this attraction and repulsion a micelle forms.
When water is poured on the clothes the hydrophobic end of micelle gets detached removing the dirt or oil with it.
Hence the polar water soluble (hydrophilic) head is on the surface of the micelle whereas the non polar oil soluble (hydrophobic) tail remains in the center of the micelle, so option (a) is correct.
The Polar water soluble repels the oil molecule hence it cannot be present in the center , so option (b) is incorrect.
The formation of Micelle occurs when two ends are present that are hydrophobic and hydrophilic so option(c) and (d) are incorrect.

Note:
We need to know that a micelle binds the oil and dirt particles inside the sphere and when water is poured they remove the dirt with them. The outer part is the hydrophilic end and repels the water that is poured over the cloth and washes away the dirt.