Among the following the correct statements are I. Germanium exists only in traces II. $\mathrm{PbF}_4$…
Among the following the correct statements are
I. Germanium exists only in traces
II. $\mathrm{PbF}_4$ molecule is tetrahedral in shape
III. $\mathrm{GeX}_2$ is more stable than $\mathrm{GeX}_4$
II, III only
I, II only
I, II, III
I, III only
Solution
Statement I is correct as Ge and Sn exist on earth's crust in trace amounts ( $1-2 \mathrm{ppm})$.
Statement II is correct as $\mathrm{Pb}$ belongs to group 14 and thus has four valence electrons out of which all four are used to make the four $\mathrm{Pb}-\mathrm{F}$ bonds.
The resultant geometry is tetrahedral.
Statement III is incorrect as the stability of the +2 oxidation state increases down the group due to inert pair effect and is predominant for heavier elements.
Ge prefers +4 state over +2 so $\mathrm{Ge}_4$ is more stable than $\mathrm{Ge} \mathrm{X}_2$.