Question

What is the percentage of free carbon in bituminous coal?
A. 30
B. 50
C. 70
D. 90

Answer 1

Hint: First we will start discussing what the coal is, how it is formed. Then we will mention the different types of coal, their composition and uses. Using this information, we will determine the percentage of free carbon in bituminous coal.

Complete answer:
Coal is sedimentary rock, usually black in color and is combustible. It is formed mostly of carbon with different amounts of other elements such as hydrogen, sulfur, nitrogen and oxygen. A few hundred million years ago bacteria and fungi had not evolved to decompose wood completely, that partially decomposed wood turned into coal when it got buried under layers of sediment. When the bacteria developed the ability to decompose wood, the formation of coal stopped. There are many types of coal such as Peat, which is the partially decomposed organic matter. Lignite which is the most basic and the most harmful form of coal. It has about 30% carbon and is used as fuel to produce electricity. Next is Bituminous coal which has about 70% carbon content and is used for steam engines or to make coke. The last form is the Anthracite which has about 90% carbon and is used for residential space heating. We also find granite with coal, this is made completely out of carbon and is used in pencils and for lubrication. As we can see from the information provided above, Bituminous coal has 70% free carbon. Hence, the correct option is C, i.e. 70.

So, the correct answer is “Option C”.

Note:
The different types of coal have different purposes depending on their carbon content which determines the content of the smoke produced on burning them. Bituminous coal is the most common form of coal found due to the mediocre amount of carbon in it.