Question

Why does carbon form only covalent bonds with other carbon atoms

Answer 1

carbon only forms covalent bonds with carbon or any other because carbon needs four electrons it cannot loose four. nor gain four becouse protons inside do not accommodate so carbon makes Covalent bond which means sharing of electrons
Hope the answer is satisfactory

Answer 2

Carbon has 4 electrons in its outermost shell. ... Therefore, carbon completes its octet by sharing its 4 electrons with other carbon atoms or with atoms of other elements and forms covalent bond. It forms strong covalent bonds because of its small size.