Define the following
(i) Cationic detergents
(ii) Narrow spectrum antibiotics
(iii) Disinfectants

Explanation

(i) Cationic detergents: In these detergents, a major part of their molecules are cations and it is the cationic part of molecule which is invoved in their cleasing action. Example quaternary ammonium salts (chlorides, bromides, acetates etc.)
`underset("(Cetyltrimethylammonium bromide)")([CH_(3) - (CH_(2))_(15) overset(o+)(-) underset(CH_(3))underset(|)overset(overset(CH_(3))(|))(N) - CH_(3)]Br^(-))`
(ii) Narrow spectrum antibiotics: Antibiotics which are effective only against certain disease e.g., pencillin is narrow spectrum antibiotic which is effective only against disease caused by various cocci and some gramm positive bacteria.
(iii) Disinfectants: They are the chemical substances which kill micro-organisms but are not safe to be applied to the living tissues. These are generally used to kill the micro organisms present in drains, toilets, floors etc.
For example : 1% solution of phenol