Which one of the following statements is correct about diamond and graphite?

Diamond and graphite are allotropes of carbon with identical chemical properties but vastly different physical properties due to their distinct atomic arrangements [1]. Diamond possesses a rigid, three-dimensional tetrahedral structure where each carbon atom is bonded to four others, making it the hardest natural substance known [2]. In contrast, graphite consists of hexagonal layers held together by weak van der Waals forces, allowing the layers to slide over one another [1]. This structural difference makes graphite soft, smooth, and slippery, rendering it useful as a lubricant [1]. Furthermore, while diamond is an electrical insulator because it lacks free electrons, graphite is a good conductor of electricity due to the presence of delocalized electrons within its layers [3]. Therefore, the statement that diamond is hard while graphite is smooth and slippery is the only correct option.

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
3. [3] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > What you have learnt > p. 55