Question

The coal with the highest ash content is?
(A) Steam coal
(B) Lignite
(C) Coking coal
(D) Bituminous coal

Answer 1

Hint: There are four forms in which coal is available; the different forms are lignite, anthracite, bituminous and sub-bituminous. Anthracite is the best type of coal which can be used in metallurgical processes.

Complete step by step solution:
Least the carbon content in coal highest will be the ash content, to answer the above question we should know about the carbon content in different types of coal.
Bituminous coal consists of 78%-86% carbon. It also contains 17% of moisture and 12% of ash content and some amount of nitrogen. Bituminous coal also contains some volatile matter like some hydrocarbons and sulfur etc. it is also known as black coal and soft coal.
Lignite- it is also known as brown coal because it is brown in colour. It is the type of coal which has the least concentration of carbon in it which is around 20%-30%.
Steam coal- the carbon content in steam coal is about 77%-87%. It is dry coal and the heating value of steam coal is much higher than the heating value of lignite and sub-bituminous coal.
Coking coal- the carbon content is around 43%-86%. It is a type of bituminous coal.
Hence, lignite has the least carbon content which means that it has the highest ash content.

The correct option is (B).

Note: Some other types of coal are Anthracite coal which contains around 94%-98% of carbon. It is the highest ranking coal and it is also known as hard coal. The ash content and smoke content in anthracite coal are very low. It is the best coal which can be used in the metallurgical process.