CO₂ is gas while SiO₂ is solid at room temperature

Explanation

The physical states of CO₂ and SiO₂ at room temperature are primarily determined by their molecular structures. CO₂ is a gas because it consists of independent molecules held together by weak forces. On the other hand, SiO₂ is a solid due to its network covalent structure where silicon atoms are bonded to oxygen atoms in a 3D network. This network covalent bonding is the reason for SiO₂'s solid state. Option B is correct as it highlights this key difference in molecular structure. Option A is incorrect as the elemental nature of carbon and silicon is not directly related to their states. Option C is partially relevant but doesn't address the primary factor of molecular structure. Option D focuses on bond types rather than the network structure of SiO₂.