The correct order of melting points of $Al$,$Ga$,$In$ is

In group $13$ of the long form of the periodic table, an element $X$ has a boiling point of $T_2 \ (K)$ and a melting point of $T_1 \ (K)$. Identify the element $X$ for which $T_2 - T_1 \ (K)$ is maximum.

If the formula of Borax is $Na_2B_4O_x(OH)_y \cdot zH_2O$,then $x+y+z = ...........$.

Borax is actually made of two tetrahedra and two triangular units joined together and should be written as: $Na_2[B_4O_5(OH)_4] \cdot 8H_2O$. Consider the following statements about borax:
$a.$ Each boron atom has four $B-O$ bonds
$b.$ Each boron atom has three $B-O$ bonds
$c.$ Two boron atoms have four $B-O$ bonds while other two have three $B-O$ bonds
$d.$ Each boron atom has one $-OH$ group
Select correct statement$(s)$:

The number of neutrons present in the more abundant isotope of boron is $x$. Amorphous boron upon heating with air forms a product,in which the oxidation state of boron is $y$. The value of $x+y$ is ...

Which pair of oxides is acidic in nature?