A non-metal X exists in two different forms Y and Z. Y is considered the hardest natural substance, whereas Z is a good conductor of electricity. Identify Y and Z forms.

Hint: We can assume so many things in this question as Y and Z. first of all read the hints given in the question very thoroughly and find out which is the hardest metal as per current discoveries. And also as metals are considered to be good conductors, there is high possibility for Y to be a metal.

Complete step by step answer:
As per the clues regarding the identification of the unknown materials, we can make some assumptions first. Y is mentioned as the hardest natural substance. We know that diamond is the hardest natural material yet found. Therefore Y will be diamond. And Z is mentioned as a good conductor of electricity which can be related to graphite which is used as electrodes in the processes sometimes. And also both the diamonds and graphite are made using the basic atom of carbon, which is actually a non-metal which is lacking lustre and also not a conductor of electricity. Carbon and diamond and graphite are having different peculiar characteristics due to the crystal structures of each of them.

Hence Y and Z are diamond and graphite respectively.

Note: Diamonds are suitable in the use as a cutting tool and for other uses where durability is needed. Diamond is having peculiar optical characteristics such as a high index of refraction, high dispersion, and high lustre. Graphite is widely used for refractory, battery, steel and brake linings. Graphite blocks are helpful in blast furnace linings where the high thermal conductivity of graphite is very critical.