Which one of the following statements is NOT correct ?

Diamond is an allotrope of carbon characterized by a giant covalent structure where each carbon atom is tetrahedrally bonded to four others. This extended covalent network makes diamond the hardest known natural substance [2]. Unlike graphite, which has delocalized electrons that allow for electrical conductivity, diamond's valence electrons are tightly held within these covalent bonds and are not free to move. Consequently, diamond is a poor electrical conductor (an insulator), making statement 3 incorrect. Fullerene (C60) consists of carbon atoms arranged in five and six-membered rings resembling a football [1]. Graphite's layered structure, held together by weak intermolecular forces, allows layers to slide over each other, making it an effective lubricant.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Allotropes of carbon > p. 61
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Table 3.1 > p. 40