Reaction between the following pairs will produce $H_2$ except:

Among the following,the correct statements are:
$I$. $LiH, BeH_2$ and $MgH_2$ are saline hydrides with significant covalent character.
$II$. Saline hydrides are volatile.
$III$. Electron-precise hydrides are Lewis bases.
$IV$. The formula for chromium hydride is $CrH$.
The correct option is:

Which of the following statements is incorrect?

What is the sum of the number of neutrons and protons in the heaviest isotope of hydrogen?

Match the correct option from Column-$A$ and Column-$B$.

Column-$A$	Column-$B$
$(1)$ Ionic hydride	$(p)$ $BeH_2$
$(2)$ Interstitial hydride	$(q)$ $TiH$
$(3)$ Electron-precise hydride	$(r)$ $CH_4$
$(4)$ Electron-rich hydride	$(s)$ $H_2O$
	$(t)$ $B_2H_6$

Which of the following statements is correct?