Which is an amphoteric oxide?

$Ge(II)$ compounds are strong reducing agents,whereas $Pb(IV)$ compounds are strong oxidizing agents. This is due to:

Amphibole silicate structure has '$x$' number of corners shared per tetrahedron. The value of '$x$' is

Superphosphate of lime contains

Given below are two statements:
Statement $I$ : $SiO_2$ and $GeO_2$ are acidic while $SnO$ and $PbO$ are amphoteric in nature.
Statement $II$ : Allotropic forms of carbon are due to property of catenation and $p \pi-d \pi$ bond formation.
In the light of the above statements,choose the most appropriate answer from the options given below:

$P_4O_{10}$ has short and long $P-O$ bonds. The number of short $P-O$ bonds in this compound is