Question

Which is an almost pure form of carbon ?
A) Coke
B) Coal tar
C) Coal gas
D) None of these

Answer 1

Hint: Carbon forms a huge number of compounds with a large number of elements.  It is the only atom that has a high combining capacity to form compounds and molecules with other atoms and elements.  Some elements contain only carbon atoms in their structure. These are the pure forms of carbon.To answer this question, firstly we will discuss each term and then judge the answer accordingly.

Complete answer:
> Coke is a grey, hard, and porous fuel with a high carbon content and few impurities, made by heating coal or oil in the absence of air and this process is called a destructive distillation process. It is an important industrial product, used mainly in iron ore smelting, but also as a fuel in stoves and forges when air pollution is a concern.
> Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. It has both medical and industrial uses.
> Coal gas is a flammable gaseous fuel made from coal and supplied to the user via a piped distribution system. It is produced when coal is heated strongly in the absence of air. Coal gas contains a mixture of calorific gases including hydrogen, carbon monoxide, methane, ethylene and volatile hydrocarbons etc.
> Among all, Coke is a fuel with few impurities and a high carbon content, usually made from coal. It is the solid carbonaceous material derived from destructive distillation of low-ash, low-sulfur bituminous coal. Coal tar and coal gas contain more impurities than coke.

Hence, option (a) is correct.

Note: Actually purest form of carbon is diamond because the composition of the diamond is homogeneous and is consistent throughout but among the given options coke is purest.