Describe the following substance with one suitable expample of each type :
(i) Non - ionic detergents
(ii) Food preservatives
(iii) Disinfecants

Explanation

(i) Nonionic detergents like esters of high molecular mass formed by reaction between polyethylene glycol and stearc acid. Detergents are preferred over soaps as they work even in hard water and acidic pH where soaps become insoluble . They have powerful cleansing action.
(ii) Preservatives : Preservatives are the substances used to prevent spoilage of food due to microbial growth during storage . the most common preservatives used are sodiun benzoate sodium metabisulphite ect . salt -sugar and oils also act as food preservatives and have been used for many years.
(iii) Disinfectants : these are chemical substances used to kill micro - organisms in rooms, toilets drums, stores , ect . these are not safe to be applied to the living tissues as they are quite strong . For example (i) `1%` solution of phenol (ii) solution of o-, m- and p- cresols in soapy water is called lysol and is used as a disinfectant.