Give reason for the following: (a) Silicon counts among metalloids

Give reason for the following:
1.Silicon counts among metalloids.
2.Carbon is not used for making aluminium from aluminium oxide.
3.For making hydrogen by reaction with hydrochloric acid, granulated zinc is preferred to a block of zinc.

1.Silicon poses both quality of metal and non-metal. Typically, silicon has metallic appearance, but it is brittle and only fair conductor of electricity.

2.Aluminium is placed high up in activity series, it means, aluminium is reactive, and cannot be isolated by heating its compound with carbon. This is because, the highly reactive metals have greater affinity for oxygen than for carbon.

3.The granulated zinc is preferred to block of zinc in preparation of hydrogen gas because granulated zinc has more surface area exposed to the acid, so the reaction occurs more rapidly.