Define the following:

(a) Anionic detergents

(b) Narrow spectrum antibiotics

(c) antacids

(a) A detergent is said to be anionic when the large part of its molecule is an anion and is involved in the cleansing action. The anionic detergents are also effective in slightly acidic solutions. In slightly acidic solutions, they form an alkyl hydrogen sulphate which is a soluble material. In contrast, soaps react with acidic solutions to form insoluble fatty acids.

(b) The class of antibiotics which are effective against only certain specific diseases and can attack only certain types of cocci and other gram-positive bacteria are referred as narrow-spectrum antibiotics. Example- Penicillin.

(c) Any drug or medicine which is administered to counteract the effects of excess acids in the stomach is called as antacids. Example- ranitidine, cimetidine etc.