Question

A soap molecule forms micelle. Which of the following is not true?
A. The long non-polar end of soap gravitates towards and surrounds the dirt and absorbs the dirt in it.
B. The short polar end with the carboxylate ion turns the water away from the dirt.
C. The soap molecule helps in dissolving the dirt in water.
D. The end of soap molecule with carboxylate group is oil soluble.

Answer 1

Surface active substance which lowers the surface tension of water known as surface active substance. Soap is the sodium or potassium salt of higher fatty acids. Soaps are made from fats and oils, or their fatty acids, by treating them chemically with a strong alkali.

Complete answer:
Soap is a cleansing agent created by the chemical reaction of a fatty acid with an alkali metal hydroxide. Soap has a general chemical formula ${{RCOOX}}$. Soaps are the product of the reaction between a fat and sodium hydroxide.
The name of soap molecules is micelles. It has a hydrophilic group and hydrophobic group. Hydrophobic end is attached to the dust, oil, grease, dirt or the materials which we want to remove, detaching takes place, get suspended in water and can easily be removed. Hydrophilic heads dissolve in water. The hydrocarbon chains are attracted to each other by dispersion forces and cluster together, forming structures called micelle. In these micelles, the hydrophilic end forms a negatively-charged spherical surface, with the hydrocarbon chains inside the sphere. Thus soap micelle repels each other and remains dispersed in water. When soaps and oil are mixed, non-polar portions of micelle break up the non-polar oil molecules. Thus the grease and oil and the dirt attached to them are caught inside the micelle and can be rinsed away.
Carboxylic group is a hydrophilic group which means water lovable and insoluble in oil.

So, the correct answer is Option D.

Note: Soap is an excellent cleanser which often occurs in the form of solid bars or in liquid form. Soap acts as an emulsifier. An emulsifier is capable of dispersing one liquid into another immiscible liquid. Hydrophilic end interacts with water via ion-dipole interactions and hydrogen bonding.