Give an appropriate term for the following:

(a) Substances whose atoms or molecules are arranged in a definite pattern.

(b) Different forms of an element found in the same physical state.

(c) The property by which atoms of an element link together to form long chain or ring compounds.

Name the following:

(a) The hardest naturally occurring substance.

(b) A greyish black non-metal that is a good conductor of electricity.

(c) The third crystalline form of carbon.

Define the following terms:

(a) Allotropy

(b) Carat

(c) Crystal

(d) Catenation

Answer the following in brief :

Why is graphite a good conductor of electricity but not diamond?