Is shampoo acidic or basic?

Hint: Hair has disulphide bond linkages, the higher pH containing shampoos when used results in the breakage of these bonds and results in hair loss and dissolving of hair. The shampoo has to be the pH levels between $ 3.7 $ to $ 5.5 $ . The ideal shampoo has a pH of $ 5.5 $ . Based on the pH levels, the nature of shampoo can be determined.

Complete answer:
The chemical compounds are classified based on nature. Based on the values of pH, the compounds were classified as basic, acidic and neutral substances.
pH scale was introduced by Sorensen, has the values from $ 1 $ to $ 14 $ . The compounds containing the pH value below $ 7 $ are termed as acidic compounds. The compounds containing the pH value above $ 7 $ are termed as basic compounds. The compounds containing the pH value exactly equal to $ 7 $ are termed as neutral compounds.
Shampoo consists mainly of citric acid as an ingredient. Citric acid is a tricarboxylic acid consisting of three carboxylic acid groups along with one hydroxyl group. The pH of citric acid is around $ 5 $ .
As the shampoo has citric acid as a main ingredient, and has a pH value falls as acidic. Shampoo is considered acidic.

Note:
There were different types of shampoos available. But the main ingredient in shampoo is citric acid. Based on the pH of citric acid, the pH of shampoo can be determined. Shampoo is a basic hair care product. The pH of a shampoo never falls on basic compounds i.e., above the value of $ 7 $ as the alkaline shampoo can have a severe effect on hair.