SiO2 is solid but CO2 is a gas at room temperature.
Carbon is able to form pπ – pπ bond with O atom and constitute a stable non - polar molecule O = C = O. Due to weak inter particle force its boiling point is low and it is gas at room temperature. Si on the other hand is not able to from pπ – pπ bond with O atoms because of its relatively large size. In order to complete its octet Si is linked to four O atoms around it by sigma bond & these constitutes network structure, which is responsible for its solidity.
