Conc. $HNO_3$ can be stored in a container of

Select the incorrect statement:
$a$. $PCl_5$ forms a weak monobasic acid during hydrolysis.
$b$. In $B_3N_3H_6$,nucleophilic attack occurs on the $B$ atom.
$c$. $Al_2Cl_6$ is a polar and planar molecule.
$d$. In $AlF_3$,the hybridization of $Al$ is $sp^2$.

Select the correct statements for diborane $(B_2H_6)$:
$1.$ Boron is approximately $sp^3$ hybridized.
$2.$ The $H-B-H$ bridge angle is $180^o$.
$3.$ There are two terminal $B-H$ bonds for each boron atom.
$4.$ There are only $12$ bonding electrons available.

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

What are the freezing and boiling points of ammonia $(NH_3)$?

Alumina $(Al_2O_3)$ is: