Which of the following is electron-deficient?

Aluminium reacts with $NaOH$ and forms compound '$X$'. If the coordination number of aluminium in '$X$' is $6$,the correct formula of $X$ is:

$A$ black coloured element with $ns^2 np^1$ outer electronic configuration cannot react with air in its crystalline form. However,in amorphous form,it gives an oxide in air which is acidic in nature. Identify the element.

Give the origin and occurrence of group $13$ elements.

Consider the following reactions (not balanced):
$BF_3 + NaH \xrightarrow{450 \ K} X + NaF$
$X + H_2O \longrightarrow Y + H_2 \uparrow$
The correct statements about $X$ and $Y$ are:
$I$. $X$ is an electron-deficient molecule
$II$. In $X$,$B-B$ bond is present
$III$. $Y$ is a weak tribasic acid
$IV$. $Y$ acts as a Lewis acid

Choose the incorrect statement/reaction.