Anhydrous $AlCl_3$ is obtained from

In which of the following molecules is a hydrogen bridge bond present?

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.

What are electron-deficient compounds? Are $BCl_3$ and $SiCl_4$ electron-deficient species?

Which of the following statements are not correct?
$i$. Atomic radius of $Ga$ is less than that of $Al$
$ii$. The order of ionization enthalpy of group $13$ elements is $B > Al > Ga > In > Tl$
$iii$. Boron trioxide is amphoteric in nature

The number of acidic protons present in $H_3PO_2$,$H_3PO_3$ and $H_3PO_4$ respectively,are .....