Question

Chemistry plays a very important role in our everyday life. Beginning from morning when we use toothpaste to brush our teeth and throughout the day we use a large number of materials which have been provided to us by R & D (Research and development) carried out in the field of chemistry. 

Now, answer the following questions : 

(i) Why should we use iodized salt ? 

(ii) Why should our toothpaste contain fluoride? 

(iii) What are the relative advantages and disadvantages of using soaps and detergents? 

(iv) Why earlier leaded petrol was used but now a days unleaded petrol is used?

Answer 1

(i) Iodine is needed to protect us from thyroid disorders. 

(ii) Fluoride protects our gums and prevents tooth decay. 

(iii) Soap is a good cleansing agent & is 100% biodegradable. As a result, it does not cause any pollution problem. However, soaps have two disadvantages. Firstly, they cannot be used in hard water. Secondly, they cannot be used in acidic solution. However, the detergents have one disadvantage that they are not completely biodegradable and hence cause water pollution. 

(iv) Earlier, tetraethyl lead was added to petrol by the oil companies to act as anti-knocking agent. But on decomposition, it produces lead which is poisonous. Hence, its use has been stopped. Quality of petrol has been improved by other methods.