Give reasons for the following
(a) `C Cl_(4)` is immiscible in water, whereas `SiCl_(4)` is easily hydrolysed.
(b) Carbon has a strong tendency for catenation compared to silicon.

Explanation

(i) `"CCl"_(4)` is a covalent compound while `H_(2)O`is a polar compound. Therefore it is insoluble in water alternatively, `"CCl"_(4)` is insoluble in water because carbon does not have d-orbitals to accommodate the electrons donated by oxygen atom of water molecules. As a result , there is no interaction between `"CCl"_(4)` and water molecules and hence `"CCl"_(4)` is insoluble in water. On the other hand, `SiCl_(4)` has d-orbitals to accomendate the lone pair of electrons donated by oxygen atom of water molecules. As a result, there is a strong intereaction between `SiCl_(4)` and water molecules . Consequently, `SiCl_(4)` undergoes hydrolysis by water to form silicic acid.
`"CCl"_(4) +H_(2)O rarr "No reaction", SiCl_(4)+4H_(2)Orarr underset("Silicate acid")(Si(OH)_(4))+4HCl`
(ii) The bond dissociation energy decreases rapidly as the atomic size increases. Since the atomic size carbon is much smaller (77 pm) as compared to that of silicon (118 pm), therefore , carbon -carbon bond dissociation energy is much higher `(348 kj mol^(-1))` than than that of silicon-silicon bond `(297 kJ mol^(-1))` . Because of much stronger C-C bonds as copared to Si-Si bonds, carbon has a much higher tendency for catenation than silicon.