Which of the following is a covalent network solid formed from carbon?

• A. Diamond
• B. Graphite
• C. Carbon dioxide (CO_{2})
• D. Buckminsterfullerene (C_{60})

Answer: (A)

Verified step by step guidance

1. Understand the concept of a covalent network solid: it is a structure where atoms are bonded by a continuous network of covalent bonds extending throughout the material, resulting in a very hard and high melting point solid.
2. Analyze each option to determine if it forms a covalent network solid:
3. Diamond: Each carbon atom is tetrahedrally bonded to four other carbon atoms in a 3D network, forming a strong covalent network solid.
4. Graphite: Carbon atoms are bonded in layers with strong covalent bonds within layers but weak van der Waals forces between layers, so it is not a 3D covalent network solid but a layered structure.
5. Carbon dioxide (CO_{2}): It is a molecular solid composed of discrete molecules held together by weak intermolecular forces, not a covalent network solid.
6. Buckminsterfullerene (C_{60}): It consists of discrete spherical molecules held together by weak intermolecular forces, not a continuous covalent network.