Compare the shapes of the following pairs of molecules or ions and suggest reasons for the differences in each pair:

${\mathrm{CCl}}_4$ and ${\mathrm{TeCl}}_4$

Compare the shapes of the following pairs of molecules or ions, and suggest reasons for the differences in each pair:

${\mathrm{CO}}_2$ and ${\mathrm{NO}}_2$

Compare the shapes of the following pairs of molecules or ions, and suggest reasons for the differences in each pair

${\mathrm{SiF}}_4$ and ${\mathrm{ICl}}_4^{-}$

Give equations to show the reactions between $\mathrm{Sn}$and ${\mathrm{O}}_2$.