Final answer:
Graphite is not a simple molecular covalent substance. It is a non-metallic, covalent network solid.
Step-by-step explanation:
A simple molecular covalent substance is made up of molecules that contain covalent bonds. These molecules are typically low in melting and boiling points and do not conduct electricity.
Out of the given options, Graphite is not a simple molecular covalent substance. Graphite is a form of carbon in which the carbon atoms are arranged in a hexagonal lattice. It is a non-metallic, covalent network solid, different from the other options which are simple molecular covalent substances.