Question

Out of the following which form of coal has the highest content of carbon ?
A. Anthracite
B. Lignite
C. Sub-Bituminous
D. Bituminous

Answer 1

Hint:We should know coal is a combustible rock and, along with oil and natural gas, it is one of the three most important fossil fuels. More the carbon content present in coal more is the temperature at the time of its combustion. Now you can recall properties of the types of coal.

Complete step-by-step answer:
We will talk about each type of coal in our following discussion -
Peat - Peat is an organic sediment. Burial, compaction, and coalification will transform it into coal, a rock. It has a carbon content of less than 60% on a dry ash-free basis.
Lignite - Lignite is the lowest rank of coal. It is a peat that has been transformed into a rock, and that rock is a lump of brown-black coal. Lignite sometimes contains recognizable plant structures. It has a carbon content of between 60 and 70% on a dry ash-free basis.
Sub-bituminous coal - Sub-bituminous coal is a lignite that has been subjected to an increased level of organic metamorphism. This metamorphism has driven off some of the oxygen and hydrogen in the coal. That loss produces coal with a higher carbon content (71 to 77% on a dry ash-free basis).
Bituminous - Bituminous is the most abundant rank of coal. Bituminous coal is formed when sub-bituminous coal is subjected to increased levels of organic metamorphism. It has a carbon content of between 77 and 87% on a dry ash-free basis.
Anthracite - Anthracite is the highest rank of coal. Unlike other types of coal, it is usually considered to be a metamorphic rock. It has a carbon content of over 87% on a dry ash-free basis.

Therefore, we can conclude that the correct answer to this question is option A.

Note:These are some important points related to coal -
Bituminous coal is often referred to as "soft coal"; however, this designation is a layman's term and has little to do with the hardness of the rock.
Anthracite is often referred to as "hard coal"; however, this is a layman's term and has little to do with the hardness of the rock.