Thermodynamically most stable allotrope of carbon is

In the dimer of phosphorus pentaoxide $(P_4O_{10})$,what is the correct order of the number of $P-O-P$,$P=O$,and $P-P$ bonds?

The option$(s)$ with only amphoteric oxides is(are)
$[A]$ $Cr_2O_3, BeO, SnO, SnO_2$
$[B]$ $Cr_2O_3, CrO, SnO, PbO$
$[C]$ $NO, B_2O_3, PbO, SnO_2$
$[D]$ $ZnO, Al_2O_3, PbO, PbO_2$

What is produced by the hydrolysis of $(Me)_2SiCl_2$?

$A$ crystalline solid $X$ reacts with dil. $HCl$ to liberate a gas $Y$. $Y$ decolourises acidified $KMnO_4$. When a gas $Z$ is slowly passed into an aqueous solution of $Y$,colloidal sulphur is obtained. $X$ and $Z$ could be,respectively

What are the $C-C$ single bond length and double bond length in fullerene?