Which of the following imparts a green colour to the burner flame?

Consider the following reactions.
$Na_{2}B_{4}O_{7} \xrightarrow{\Delta} 2 X + Y$
$CuSO_{4} + Y \xrightarrow{\text{Non-Luminous flame}} Z + SO_{3}$
$2Z + 2X + \text{Carbon} \xrightarrow{\text{Luminous flame}} 2Q + Na_{2}B_{4}O_{7} + CO$
The oxidation states of $Cu$ in $Z$ and $Q$, respectively are:

$X$ reacts with aqueous $NaOH$ to form $Y$ and releases $H_2$ gas. When the aqueous solution of $Y$ is heated at $323 \ K - 333 \ K$ and $CO_2$ gas is passed through it,it yields $Al_2O_3 \cdot xH_2O$ (often represented as $Al(OH)_3$) and $Z$. Heating $Z$ at $1200 \ ^\circ C$ gives $Al_2O_3$. Identify $X, Y,$ and $Z$.

The first ionization enthalpy values (in $kJ\, mol^{-1}$) of group $13$ elements are:

Element	$B$	$Al$	$Ga$	$In$	$Tl$
Ionization Enthalpy	$801$	$577$	$579$	$558$	$589$

How would you explain this deviation from the general trend?

The acidic strength of boron trihalides follows the order:

Which one of the following statements is not true regarding diborane $(B_2H_6)$?