Which is the best description of the bonding present in silicon dioxide, \({\text{Si}}{{\text{O}}_{\text{2}}}\)?

A.     Each silicon atom forms four single covalent bonds to oxygen atoms.

B.     Each silicon atom forms two double covalent bonds to oxygen atoms.

C.     Each silicon atom forms two single covalent bonds to oxygen atoms.

D.     Each silicon atom forms four double covalent bonds to oxygen atoms.

A

This was the question that caused candidates the most trouble, with a difficulty index of 5%. It would appear from the responses that about 80% of the candidates believe that the structure of silicon dioxide is identical to that of carbon dioxide. The discrimination index, at 0.04, was very low and this would seem to indicate that many candidates are not being made aware of these important structural differences.