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

Which one of the following statements is not correct?

$X$ 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 bonding in diborane $(B_2H_6)$ can be described by

Explain the nature of boric acid $(H_3BO_3)$ as a Lewis acid in water. The structure of $H_3BO_3$ is given below:
$H-O-B(OH)_2$

$Na_2B_4O_7$ $\xrightarrow{x} H_3BO_3$ $\xrightarrow{\Delta} B_2O_3$ $\xrightarrow{y} B$
Here $X$ and $Y$ are respectively: