What is charcoal? Give its different forms.

Charcoal is black, soft and highly porous substance which exists in the following forms:
(i) Wood charcoal: It is obtained by heating wood or nutshells strongly in a limited supply of air and volatile gases are allowed to escape. It is mainly elemental carbon (95 to 98%). It is used in the gas masks to remove poisonous gases.
(ii) Animal charcoal: It is also called bone charcoal and obtained by destructive distillation of bones. It contains 10 to 12% by carbon and rest is calcium phosphate. Animal charcoal is generally used to absorb colouring matter from sugarcane juice and also to decolourise certain impure compounds.
(iii) Sugar charcoal: It is formed by the action of concentrated H₂SO₄ on sucrose (C₁₂H₂₂O₁₁).
Sugar charcoal is a very good adsorbent to remove colouring matter.