Borax is converted into crystalline boron by the following steps :
$Borax$ $\xrightarrow{HCl} (X)$ $\xrightarrow{\Delta} B_2O_3$ $\xrightarrow{\Delta, Y} B$
Identify $X$ and $Y$ respectively.

The element that combines with oxygen to give an amphoteric oxide is

The stability of $+1$ oxidation state among $Al$,$Ga$,$In$ and $Tl$ increases in the sequence:

Consider the compounds,$BCl_3$ and $CCl_4$. How will they behave with water? Justify.

Boron does not form $B^{3+}$ cation easily. It is due to

When metal $X$ is treated with sodium hydroxide,a white precipitate $(A)$ is obtained,which is soluble in excess of $NaOH$ to give soluble complex $(B)$. Compound $(A)$ is soluble in dilute $HCl$ to form compound $(C)$. The compound $(A)$ when heated strongly gives $(D)$,which is used to extract metal. Identify $(X), (A), (B), (C)$ and $(D)$. Write suitable equations to support their identities.