Explain the metallic character of group 14 elements.

Among the following, the number of halide(s) which is/ are inert to hydrolysis is

(A) ${\mathrm{BF}}_3$
(B) ${\mathrm{SiCl}}_4$
(C) ${\mathrm{PCl}}_5$
(D) ${\mathrm{SF}}_6$

Identify the correct statements from the following.

i) Quartz is a piezoelectric material
ii) All group $14$ tetrachlorides except ${\mathrm{CCl}}_4$ are easily hydrolyzed in water.
iii) The $\mathrm{C}-\mathrm{C}$ bond distance within the layer of graphite is $154\mathrm{pm}$.
iv) ${\mathrm{SiO}}_2$ is soluble in aqueous $\mathrm{HCl}$ solution.

Explain the following :

Carbon shows catenation property but lead does not.

Explain why is there a phenomenal decrease in ionization enthalpy from carbon to silicon?