Which of the following statement$(s)$ is/are correct:
$A$. $NaH$ is a non-volatile hydride
$B$. $MgH_2$ is a polymeric hydride
$C$. $NH_3$ is an electron-precise hydride
$D$. $H_2O$ is an electron-rich hydride

Hydrogen resembles halogens in many respects for which several factors are responsible. Of the following factors,which one is most important in this respect?

During the water-gas shift reaction:

The gaseous product$(s)$ expected at room temperature by the reaction of sodium borohydride and boron trifluoride under anhydrous conditions is/are:

Arrange the following:
$(i)$ $CaH_2$,$BeH_2$ and $TiH_2$ in order of increasing electrical conductance.
$(ii)$ $LiH$,$NaH$ and $CsH$ in order of increasing ionic character.
$(iii)$ $H-H$,$D-D$ and $F-F$ in order of increasing bond dissociation enthalpy.
$(iv)$ $NaH$,$MgH_2$ and $H_2O$ in order of increasing reducing property.

In which of the following processes is the highest purity $(99.9 \%)$ hydrogen obtained?