(N/A) In $CO_{2}$, the carbon atom undergoes $sp$ hybridization. Two $sp$ hybridized orbitals of the carbon atom overlap with two $p$ orbitals of oxygen atoms to form two sigma bonds, while the other two electrons of the carbon atom are involved in $p\pi-p\pi$ bonding with oxygen atoms.
This results in a linear shape [with both $C-O$ bonds of equal length $(115 \ pm)$] with no dipole moment. Carbon can form a double bond with oxygen due to its small size.
Silicon dioxide is a covalent, three-dimensional network solid in which each silicon atom is covalently bonded in a tetrahedral manner to four oxygen atoms. Each oxygen atom is, in turn, covalently bonded to another silicon atom.
Each corner is shared with another tetrahedron. The entire crystal may be considered a giant molecule in which eight-membered rings are formed with alternate silicon and oxygen atoms. Silicon cannot form a stable $p\pi-p\pi$ double bond with oxygen due to its large size and lower electronegativity compared to carbon.