Carbon dioxide is a gas but silica is a solid because:
A. `CO_(2)` molecules are lighter than `SiO_(2)` molecules
B. carbon dioxide is composed of descreate covalent `CO_(2)` molecules whereas silica has continuous tetrahedral structure
C. `CO_(2)` is more acidic than `SiO_(2)`
D. melting point of silica is very high
