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

 (i) Tranquilizers

 (ii) Food preservatives

 (iii) Synthetic detergents

(i) Tranquillizers: A tranquillizer is a drug that acts on the central nervous system and is used to calm, decrease anxiety, or help a person to sleep. Often called depressants because they suppress the central nervous system and slow the body down, they are used to treat mental illness as well as common anxiety and sleeplessness.

There are two types or classes of tranquillizers:

(a) Major tranquillizers example phenothiazine
(b) Minor tranquillizers example schizophrenia

(ii) Food Preservatives: These are the chemical substances which are added to the food materials to prevent their spoilage and to retain their nutritive value for long periods. Example: Vinegar Food preservation involves preventing the growth of bacteria, fungi (such as yeasts), or other micro-organisms as well as retarding the oxidation of fats that cause rancidity.

(iii) Synthetic detergents: Synthetic detergent is a cleansing substance that acts similarly to soap but is made from chemical compounds rather than fats and lye. These detergents were developed in order to replace soaps for cleaning, to overcome some of the soap's shortcomings. These can be used both in hard and soft water. Example: Sodium p-dodecyl benzene sulphonate

Synthetic detergents can be classified as:
Anionic: Having negatively charged head and widely used due to cost and performance. Uses include:

(i)Laundry detergents
(ii)Dishwashing liquids
(iii)Oven cleaners

Cationic: Having a positively charged head. Uses include:

(i) Cleaning plastics
(ii)Hair shampoos
(iii)Fabric softeners and conditioners

Non-ionic or neutral: Having an uncharged head. Uses include:

(i)Car shampoos
(ii)Dishwasher detergents
(iii)Cosmetics