Explain the structure and stability of chlorides of group iV- A elements

Group IV elements form tetrahalides of the type MX_4,except PbI₄.These halides are typically covalent,tetrahedral in structure and are very volatile.Carbon forms carbon tetrachloride(CCl₄) which is extensively used as a solvent and in the manufacture of freons.The carbon halides are not hydrolysed under normal conditions because of non-availability of d-orbitals.Other chlorides can be hydrolysed in water.
SiCl₄ + 4H₂O -----------> Si(OH)₄ + 4HCl
GeCl₄ hydrolysed less readily.SnCl₄ and PbCl₄ hydrolyse in dilute solutions but hydrolysis is often incomplete. PbCl_{4 i}s unstable .
Carbon forms a number of catenated halides the best known is being teflon.Silicon forms polymers(SiCl₂)n by passing the tetrahalide over heated silicon.Germanium forms the dimer Ge₂Cl_6,but Sn and Pb do not form any catenated halides.
These elements also form dihalides and there stability order is -
CX₂<<SiX₂<GeX₂<SnX₂<PbX₂
PbX₂ is more stable than PbX_4, while GeX₄ is more stable than GeX₂.