Question

How is coal formed?

Answer 1

Hint: Coal is a sedimentary rock that is black or brownish black in colour and is combustible which means that it can be burnt in air. Carbon is the basic material which forms coal however it contains other elements like hydrogen, sulfur, oxygen and nitrogen.

Complete answer: It takes a significant amount of time, around a few million years, for the formation of coal. It is believed that the first coal bearing rock appeared about 290 to 360 million years ago and the time period when this appeared is known as the Carboniferous period or the ‘coal bearing’ period.
Swampy wetlands where the groundwater is near or sl;ightly above the topsoil is where the formation of coal begins. Due to this the flora present there produces organic matter quickly. The production of organic matter is faster than it can be decomposed. Layers of organic matter are buried after they have been accumulated. These organic matter is what ultimately becomes coal. Sun provides the initial energy and this energy gets trapped by dead plants.
Peat. Lignite, Bituminous and Anthracite are the four stages of coal formation. The conditions to which the plant remains are subjected to after they get buried determines the stage. The rank of the coal depends on the level of pressure and heat which it is subjected to. The higher the level of pressure and heat, the higher will be the rank.
Peat is the first stage and it is a soft and spongy substance. The second stage is lignite and it is dark brown in colour. Bituminous is the third stage and it is also known as ‘soft coal’, it is compact and is greatly used in industry. The fourth stage is known as anthracite and it is also known as ‘hard coal’ because of its high lustre and hard nature, it burns with short flame and little smoke.

Note: 1774 is believed to be the date since when coal has been mined in India and now India coal is mined second fastest. In 2018 around 716 million metric tons of coal was mined in India.