In the following reactions:
$3B_2H_6 + 6NH_3 \text{ (excess)} \xrightarrow{\Delta} 2B_3N_3H_6 + 12H_2$
$6NaH + 2BF_3 \xrightarrow{450 \ K} B_2H_6 + 6NaF$
$B_2H_6 + 6H_2O \longrightarrow 2H_3BO_3 + 6H_2$
$X, Y$ and $Z$ are respectively:

In which of the following molecules is a hydrogen bridge bond present?

Describe the general trends in the following properties of the elements in Groups $13$ and $14$.
$(A)$ Atomic size
$(B)$ Ionization enthalpy
$(C)$ Metallic character
$(D)$ Oxidation states
$(E)$ Nature of halides

Match the List-$I$ with List-$II$.

List-$I$ (Element)	List-$II$ (Application)
$A$. $Cs$	$I$. High temperature thermometer
$B$. $Ga$	$II$. Water repellent sprays
$C$. $B$	$III$. Photoelectric cells
$D$. $Si$	$IV$. Bullet proof vest

Choose the most appropriate answer from the options given below:

Given below are two statements:
Statement $I$: Group $13$ trivalent halides get easily hydrolyzed by water due to their covalent nature.
Statement $II$: $AlCl_3$ upon hydrolysis in acidified aqueous solution forms octahedral $[Al(H_2O)_6]^{3+}$ ion.
In the light of the above statements,choose the correct answer from the options given below:

When orthoboric acid $(H_3BO_3)$ is subjected to strong heating,the residue left is