Which of the hydrogen halides forms salts like $KHX_2$ (where $X$ is a halogen atom)?

Complete the following chemical reactions:
$(i) \ PbS_{(s)} + H_2O_{2_{(aq)}} \to $
$(ii) \ MnO_{4_{(aq)}}^{-} + H_2O_{2_{(aq)}} \to $
$(iii) \ CaO_{(s)} + H_2O_{(g)} \to $
$(iv) \ AlCl_{3_{(g)}} + H_2O_{(l)} \to $
$(v) \ Ca_3N_{2_{(s)}} + H_2O_{(l)} \to $
Classify the above into $(a)$ hydrolysis,$(b)$ redox and $(c)$ hydration reactions.

$BeH_2$ can be prepared by the reaction of

Metal hydride on treatment with water gives

Isotope$(s)$ of hydrogen which emits low energy $\beta^{-}$ particle with $t_{1/2}$ value $> 12 \ years$ is/are :

The correct order of boiling point of $H_2$,$HD$,$D_2$ and $T_2$ would be