The geometry around boron in the product '$B$' formed from the following reaction is
$BF_{3} + NaH \xrightarrow{450 \ K} A + NaF$
$A + NMe_{3} \rightarrow B$

$TlI_3$ is isomorphous with:

Which pair of oxides is acidic in nature?

Give uses of boron and its compounds.

The number of acidic protons in $H_{3}PO_{3}$ is:

$X$ 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 $Z$.