Give reasons for the following: `CO_2` is a gas whereas `SiO_2` is a solid.

Give reason for the following:- H_3PO_3 is diprotic whereas H_3PO_4 is triprotic.

Give reason for the following:- HF is liquid but HCI is gas.

CO_ 2 is a gas but SiO_2 is a solid. Give reason.

Carbon and Silicon are present in the same group. Their dioxides CO_2 and SiO_2 , show some similarities. For example both are acidic oxides. a. But, CO_2 is a gas while SiO_2 is a solid. Account. b. The basic building blocks of silicates are (SiO4)^4-tetrahedra. Differentiate Orthosilicates and Pyrosilicates. c. Silica gel is used as-a drying agent. Justify.

Give reason for the following: Electron gain enthalpy of noble gas is almost zero.

Give reasons for the following elemental phosphorus doesnot exist as P_2 molecule:- While nitrogen exist as N_2 molecule.

Carbon and silicon are present in the same group. Their dioxides CO_2 and SiO_3 show some similarities. For example both are acidic oxides. But CO_2 is a gas, SIO_2 is a solid. Account.

Describe giving reason which one.of the following pairs has the property indicated i. Fe or Cu has higher melting point ii. '(Co)^2+or '(Ni)^2+ has lower magnetic moment.

AlF_3 is a high melting solid whereas SiF_4 is a gas. Explain.