Which variety of coal can be used to recognise the traces of the plant material from which it is formed?

Correct answer: (d) Peat

Explanation

Peat is the first stage in the formation of coal. It is partly decayed plant matter, so the remains of the plants (wood, moss and roots) can still be seen in it. It has the least carbon (about 50–60%) and much moisture.

As coal forms under heat and pressure over time, its carbon content rises:

• lignite (brown coal): about 60–70% carbon;
• bituminous coal: about 70–85%, the most common;
• anthracite: about 85–95%, the best quality.