Which of the following is classified as a network solid?

• A. Carbon dioxide (CO_2)
• B. Sodium chloride (NaCl)
• C. Argon (Ar)
• D. Diamond (C)

Answer: (D)

Verified step by step guidance

1. Understand what a network solid is: A network solid is a type of solid where atoms are covalently bonded in a continuous three-dimensional network, resulting in very strong bonds throughout the structure.
2. Analyze each option based on bonding and structure: Carbon dioxide (CO_2) is a molecular solid with discrete molecules held together by weak intermolecular forces; Sodium chloride (NaCl) is an ionic solid composed of ions arranged in a lattice; Argon (Ar) is a noble gas that forms a molecular solid held together by weak van der Waals forces.
3. Recognize that diamond (C) is a form of carbon where each carbon atom is covalently bonded to four other carbon atoms in a tetrahedral arrangement, creating a giant covalent network.
4. Conclude that among the options, diamond (C) fits the definition of a network solid because of its extensive covalent bonding throughout the crystal lattice.
5. Therefore, the correct classification of a network solid in the given options is diamond (C).