Calcium imide on hydrolysis gives gas $(B)$ which on oxidation by bleaching powder gives gas $(C)$. Gas $(C)$ on reaction with magnesium gives compound $(D)$ which on hydrolysis gives again gas $(B)$. Identify $(B)$,$(C)$ and $(D)$.

Which hydride among the following is less stable?

Fill in the blanks:
$(1)$ In the crystal structure of ice, the oxygen atom is at a distance of $276 \ pm$ from four hydrogen atoms.
$(2)$ The relative proportion of tritium to protium is $1: 10^{18}$.

Identify the correct composition of water gas from the following.

Consider the following statements about the hydrides: $(I)$ Sodium hydride with water liberates oxygen gas $(II)$ Methane,silane are examples of electron precise hydrides $(III)$ Ammonia and water molecules are examples of electron deficient hydrides $(IV)$ Hydrides of beryllium and magnesium are polymeric in structure. The correct statements are:

Identify the correct statements from the following:
$I$. $B_2H_6$ is an electron deficient hydride.
$II$. $NH_3$ is an electron rich hydride.
$III$. $NaH$ is a covalent hydride.
$IV$. $YbH_{2.55}$ is an interstitial hydride.