Question

Name any two varieties of coal that have been formed due to different temperature and pressure conditions under the surface of Earth.​

Answer 1

Answer:

Types of coal

Anthracite contains 86%–97% carbon and generally has the highest heating value of all ranks of coal. ...

Bituminous coal contains 45%–86% carbon. ...

Subbituminous coal typically contains 35%–45% carbon, and it has a lower heating value than bituminous coal.