Which of the following is an electron-precise type of hydride?

Hydrogen and deuterium differ in

Pure hydrogen is obtained by carrying out the electrolysis of:

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.

The oxide which is not reduced by hydrogen is

Give uses of Dihydrogen as a fuel.