Question

Depending upon its composition, each type of coal burns differently. The "older" the coal, the harder the coal, and the greater percentage of ______ present.

Answer 1

The answer is carbon

Step-by-step explanation:

Complex molecules are made up of carbon bonded with other elements, especially oxygen and hydrogen and frequently also with nitrogen, phosphorus and sulfur. Carbon is abundant on Earth. It is also lightweight and relatively small in size, making it easier for enzymes to manipulate carbon molecules.

Answer 2

There is a higher quantity of hydrocarbons present, which are the source of energy in coal. These oils are formed from ancient plant materials and compressed down in the earth to form coal. Older coal tends to be darker, harder, and have more hydrocarbons packed in.