Which of the following are microscopic units of coal?
(A) Vitrinite (B) Clarain (C) Exinite (D) Duain (E) Inertinite
Choose the correct answer from the options given below:

Correct option is C

The microscopic units of coal are components of its maceral groups, which are organic constituents observed under a microscope. These include:
· Vitrinite (A): Derived from woody plant material and is rich in carbon.
· Exinite (C): Derived from spores, cuticles, and resin, contributing to the volatile content of coal.
· Inertinite (E): Derived from oxidized plant material, indicating high carbon content with lower reactivity.
Clarain (B) and Durain (D) are not microscopic units; they are lithotypes of coal that describe its macroscopic appearance.
Explanation:
· Coal macerals are classified into Vitrinite, Exinite, and Inertinite.
· These microscopic units contribute to the coal’s properties such as energy content, carbon reactivity, and combustion behavior.
· Understanding macerals is essential in coal geology and for assessing coal's usability for industrial purposes.
Information Booster:
1. Vitrinite has a glassy appearance and is associated with high reflectance.
2. Exinite is also known as liptinite and has high hydrogen content.
3. Inertinite is formed through charring or oxidation before burial.
4. Macroscopic coal lithotypes (e.g., Clarain, Durain) describe visible layers.
5. The proportion of macerals determines the rank and quality of coal.
Additional Knowledge:
· Clarain (B): A bright, layered coal type composed of alternating vitrinite and inertinite.
· Durain (D): A dull coal type with a higher percentage of inertinite and mineral matter.
· Macerals:
· Vitrinite reflects thermal maturity.
· Exinite indicates oil potential.
· Inertinite suggests low reactivity in combustion.