Assertion (A) : Carbon can form more compounds than any other element. Reason (R) : Carbon can exist in various allotropes.

Assertion (A) is true because carbon is a versatile element that forms the basis of all living organisms and a vast variety of compounds [c1]. This immense diversity is primarily due to carbon's unique properties of tetravalency and catenation [c1][c3]. Catenation allows carbon to form strong, stable covalent bonds with itself, creating long chains and rings that no other element exhibits to the same extent [c2]. Reason (R) is also true; carbon exists in various allotropes such as diamond, graphite, and fullerenes, which differ in their physical bonding arrangements [c4][t2]. However, the existence of allotropes (different forms of the pure element) does not explain why carbon forms millions of different chemical compounds with other elements. The large number of compounds is specifically attributed to its ability to form four bonds and link extensively with other atoms [c2][c3]. Thus, while both statements are true, R is not the correct explanation for A.

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > What you have learnt > p. 77
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > 4.2 VERSATILE NATURE OF CARBON > p. 62
3. [3] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Organic compounds > p. 63
4. [4] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Allotropes of carbon > p. 61