What is obtained by the reaction of $N_2$ with calcium carbide $(CaC_2)$?

Explain the following:
$(a)$ $CO_2$ is a gas whereas $SiO_2$ is a solid.
$(b)$ Silicon forms $SiF_6^{2-}$ ion whereas corresponding fluoro compound of carbon is not known.

$(BN)_n$ exists in

Explain the oxidation states of group $14$ elements.

Which one of the following oxides is expected to exhibit paramagnetic behaviour?

Anhydrous sample of ferric chloride is prepared by heating: