hi

 

1)CO2 is a gas but SiO2 is a solid.why?

ans:C does not have vacant d-orbitals and thus cannot form d pie-p pie bond to form a 3D structure.

 

2)C shows extensive catenation but others of the same group do not.why?

ans:C is small in size and the C-Cbond strength is high.but as we go down the group,electro negativity decreases as size increases.thus bond strength decreases and so does the catenation property.

!!!!!!!!!!!!!!!!!!!!