Which one among the following statements is correct about a solution of borax in water?

The correct statements about the compounds of boron are:
$I$. In borax bead test, the colour of cobalt metaborate is blue.
$II$. Diborane is prepared by the oxidation of sodium borohydride with iodine.
$III$. In diborane, the oxidation state of hydrogen is $+1$.
$IV$. Boric acid is a tribasic acid.

The correct statement$(s)$ for orthoboric acid $(H_3BO_3)$ is/are:
$(A)$ It behaves as a weak acid in water due to self-ionization.
$(B)$ Acidity of its aqueous solution increases upon addition of ethylene glycol.
$(C)$ It has a three-dimensional structure due to hydrogen bonding.
$(D)$ It is a weak electrolyte in water.

Diborane on hydrolysis gives a compound $X$. The correct statements about $X$ are
$I$. It is a tribasic acid
$II$. It is a weak monobasic acid
$III$. It has a layer structure
$IV$. It is highly soluble in water

Diborane reacts with $HCl$ in the presence of $AlCl_3$ and liberates:

Explain the following:
$(1)$ Gallium has higher ionisation enthalpy than aluminum.
$(2)$ Boron does not exist as $B^{3+}$ ion.