The diagrams show the structures of two oxides of Group 4 elements: silicon dioxide and carbon dioxide.
a.[4]
State two physical properties of silicon dioxide and two physical properties of carbon dioxide at room temperature, excluding their electrical conductivity.
b.[1]
State the type of chemical bonding holding the silicon and oxygen atoms together within a crystal of silicon dioxide.
c.[4]
Explain why silicon dioxide has a very high melting point whereas carbon dioxide is a gas at room temperature, in terms of their structures and bonding.