Question

(a) Describe the formation of coal.

(b) Name four types of coal with the percentage of carbon present in each.

Answer 1

(a) Formation of coal:- The formation of coal took millions of years. Coal was formed by the bacterial decomposition of ancient vegetable matter buried under successive layers of the earth. Under in action of high temperature and pressure, and in the absence of air, the decayed vegetable matter converted into coal.
(b) Types of Coal:

1. Peat: It is light brown in colour and contains only 50 – 60% carbon. It is the most inferior form of coal.
2. Lignite: it contains more than 60% carbon. It is brown in colour and harder than peat.
3. Bituminous: It has 90%, 80%, 70 – 75% carbon contents. Bituminous coal is the most common variety of coal and used as household coal.
4. Anthracite: It is the purest variety of coal. Its carbon contents vary between 92 – 98%. It is hard, dense and black, difficult to ignite.