but graphene is not an organic comound as it is make of a singe elelement

You're right, graphene is not an organic compound because it consists of a single element, which is carbon. It is a two-dimensional allotrope of carbon arranged in a hexagonal lattice. Graphene is considered an inorganic material and is known for its exceptional properties, such as high electrical conductivity, mechanical strength, and thermal conductivity. The use of the term "-ene" in graphene refers to its structure than indicating organic nature.