${\rm{N}}{{\rm{H}}_3}\;{\rm{and}}\;{{\rm{B}}_2}{{\rm{H}}_6}$

${\rm{NaH}}\;{\rm{ and }}\;{\rm{Ca}}{{\rm{H}}_2}$

${\rm{NaH }}\;{\rm{and }}\;{\rm{N}}{{\rm{H}}_3}$

${\rm{Ca}}{{\rm{H}}_2}\;{\rm{and}}\;{{\rm{B}}_2}{{\rm{H}}_6}$

Exothermic change

Endothermic change

Nuclear change

Photochemical change

Carbon

Hydrogen

Oxygen

Nitrogen

Deuterium

Helium

Tritium

Hydrogen

$Mg$

$Zn$

$Fe$

$Ag$

$75{\rm{\% }}\;{\rm{ ortho}}\;{{\rm{H}}_2} + 25{\rm{\% }}\;{\rm{para}}\;{{\rm{H}}_2}$

$25{\rm{\% }}\;{\rm{ ortho}}\;{{\rm{H}}_2} + 75{\rm{\% }}\;{\rm{ para}}\;{{\rm{H}}_2}$

$50{\rm{\% }}\,{\rm{ortho}}\;{{\rm{H}}_2} + 50{\rm{\% }}\;{\rm{ para}}\;{{\rm{H}}_2}$

$99{\rm{\% }}\;{\rm{para}}\;{{\rm{H}}_2} + 1{\rm{\% }}\;{\rm{ortho}}\;{\rm{ }}{{\rm{H}}_2}$

a/2

a/√2

a/4

√3a/4

Its electropositive character

Its affinity for non-metal

Its reducing character

Its metallic character

${\rm{Liq}}{\rm{.}}{{\rm{H}}_2} + {\rm{Liq}}{\rm{.}}{{\rm{O}}_2}$

${\rm{Liq}}{\rm{.}}{{\rm{N}}_2} + {\rm{Liq}}{\rm{.}}{{\rm{O}}_2}$

${\rm{Liq}}{\rm{.}}{{\rm{H}}_2} + {\rm{Liq}}{\rm{.}}{{\rm{N}}_2}$

${\rm{Liq}}{\rm{.}}{{\rm{O}}_2} + {\rm{Liq}}{\rm{.Ar}}$

Hydrogen has same ionization potential as sodium

Hydrogen has same electronegativity as halogens

It will not be liberate at anode

Hydrogen has oxidation state +1, zero and -1

$1:1$

$1:2$

$2:1$

$9:4$