Which one among the following is not a form of carbon?

Carbon exists in several allotropic forms, which are different physical arrangements of the same element. Graphite is a well-known allotrope consisting of hexagonal layers held by weak van der Waals forces [2]. Graphene is a single two-dimensional layer of graphite, characterized by its sp2 hybridized carbon atoms [2]. Fullerenes, such as the C-60 buckyball, represent another class of carbon allotropes where atoms are arranged in spherical or ellipsoidal shapes resembling a football [2]. In contrast, Quartz is not a form of carbon; it is a mineral composed of silicon and oxygen atoms in a continuous framework of SiO4 silicon-oxygen tetrahedra. While carbon can form compounds with oxygen, quartz is chemically distinct from the elemental allotropes of carbon [4]. Therefore, quartz is the only option that is not a form of carbon.

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 4: Carbon and its Compounds > 4.2 VERSATILE NATURE OF CARBON > p. 62
4. [4] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > What you have learnt > p. 77