What are the following substances? Give one example of each.

(i) Food preservatives

(ii) Synthetic detergents

(iii) Antacids

(i) Food Preservatives: These are the chemical substances which are added to the food materials to prevent their spoilage due to microbial growth and to retain their nutritive value for a long time. Sodium benzoate, sodium metabisulphite are some common preservatives. Preservatives prevent rancidity and kill or inhibit the growth of the microorganism.

(ii) Synthetic Detergents: Detergents are cleaning agents which have all the properties of soaps, but actually do not contain any soap e.g., sodium dodecylbenzene sulphonate. These can be used both in soft and hard water as they give foam even in hard water.

Detergents are mainly classified into three categories:

(i) Anionic detergents

(ii) Cationic detergents

(iii) Non-ionic detergents

(iii) Antacids: These are the chemical substances which neutralize the excess acid and raise the pH to an appropriate level in the stomach. Sodium hydrogen carbonate or a mixture of aluminium and magnesium hydroxide are some common antacids.