Understanding Coal and its Carbon Content

Coal is a fossil fuel formed from the remains of plants over millions of years. As plant matter undergoes burial, pressure, and heat, it transforms through different stages. This process, called coalification, increases the carbon content and changes the properties of the coal.

The degree of transformation determines the rank of the coal. Higher rank coal has been subjected to more heat and pressure, resulting in higher carbon content and lower moisture content. The main types of coal, in order of increasing rank, are:

1. Peat
2. Lignite (often grouped with Sub-bituminous)
3. Sub-bituminous coal
4. Bituminous coal
5. Anthracite

The question asks for the increasing order of carbon content among specific types: Peat, Sub-bituminous coal, Bituminous coal, and Anthracite.

Let's look at the approximate carbon content ranges for these types:

Based on these percentages, we can see that the carbon content increases significantly from Peat to Anthracite.

Therefore, the increasing order of carbon content is:

Peat < Sub-bituminous coal < Bituminous coal < Anthracite

This order corresponds directly to the increasing rank of these coal types.

Comparing this sequence with the given options, the correct order representing the increase in carbon content is Peat < Sub-bituminous coal < Bituminous coal < Anthracite.