(i) $BeH_2$ is significantly covalent, $CaH_2$ is ionic and $TiH_2$ is metallic hydride. Hence, increasing electrical conductance : $BeH_2$ < $CaH_2$ < $TiH_2$ (ii) Electronegativity decreases as Li > Na > Cs. Thus, increasing ionic character : LiH < NaH < CsH. (iii) Due to lone pairs of F, bond pairs experience repulsion, hence, F–F has low bond dissociation energy. In D–D, due to higher nuclear attraction bond dissociation energy is geater than H– H. Increasing bond dissociation enthalpy : F–F < H–H < D–D. (iv) NaH is ionic hydride. $MgH_2$ and $H_2O$ are covalent hydrides but OH bond in $H_2O$ is more stronger. Hence, increasing reducing power : H2O < $MgH_2$ < NaH.