$N{a_2}{B_4}{O_7}\xrightarrow{x}{H_3}B{O_3}\xrightarrow{\Delta }{B_2}{O_3}\xrightarrow{y}B$

Here $X, Y$ are respectively

The correct statements among $I$ to $III$ regarding group $13$ element oxides are,

$I$. Boron trioxide is acidic

$II$. Oxides of aluminium and gallium are amphoteric

$III$. Oxides of indium and thallium are basic

Aluminium trifluoride is insoluble in anhydrous $HF$ but dissolves on addition of $NaF$. Aluminium trifluoride precipitates out of the resulting solution when gaseous $BF $$_{3}$ is bubbled through. Give reasons.

Aluminium chloride exists as dimer, $A{l_2}C{l_6}$ in solid state as well as in solution of non-polar solvents such as benzene. When dissolved in water, it gives

$AlF_3$ is soluble in $HF$ only in presence of $KF.$ It is due to the formation of

White fumes appear around the bottle of anhydrous aluminium chloride. Give reason.