Which one of the following is not true for the form of car bon known as diamond?

Diamond and graphite are allotropes of carbon with distinct physical properties due to their bonding structures. Diamond is the hardest known natural substance because each carbon atom is bonded to four others in a rigid, three-dimensional tetrahedral network [1]. In contrast, graphite consists of hexagonal layers held by weak van der Waals forces, making it soft and slippery [1]. Both are pure forms of carbon, thus containing the same carbon percentage. Regarding conductivity, graphite is an excellent electrical conductor because each carbon atom bonds to only three others, leaving delocalized pi electrons free to move between layers [1]. Diamond, however, has all its valence electrons localized in strong sigma bonds, making it an electrical insulator. Therefore, the statement that diamond is a better electrical conductor than graphite is false. Additionally, diamond's tetrahedral structure is isotropic, meaning carbon-carbon distances are identical in all directions.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Allotropes of carbon > p. 61