Answer the following case-based question given below:
 
Most dirt is oily and as you know, oil does not dissolve in water. The molecules of soap are sodium or potassium salts of long-chain carboxylic acids. The ionic end of soap interacts with water while the carbon chain interacts with oil.
 
The soap molecules, thus form structures called micelles, where one end of the molecules is towards the oil droplet while the ionic end faces outside. This forms an emulsion in water. The soap micelle thus helps in pulling out the dirt in water and we can wash our clothes clean.
 
a. What is a hydrophobic end?
 
b. When soap or detergent is dissolved in water, the molecules form clusters known as
 
c. Detergents are preferred over soaps in hard water because:
 
d. What are scums?