Calculate normality of ${\mathrm{H}}_2{\mathrm{SO}}_4$ solutions if $50\mathrm{ml}$ of it completely neutralises $250\mathrm{ml}$ of $0.1\mathrm{N} \mathrm{Ba}(\mathrm{OH}{)}_2$ solutions.

Assign oxidation number to the underlined element in the following species:

$\mathrm{NaH}\underline{\mathrm{S}}{\mathrm{O}}_4$.

Assign oxidation number to the underlined element in the following species:

${\mathrm{H}}_4{\underline{\mathrm{P}}}_2{\mathrm{O}}_7$

Assign oxidation number to the underlined elements in each of the following species:

${\mathrm{K}}_2\underline{\mathrm{Mn}}{\mathrm{O}}_4$.

Assign the oxidation number to the underlined element in the following species:

$\mathrm{Ca}{\underline{\mathrm{O}}}_2$.

Assign oxidation number to the underlined elements in each of the following species:

$\mathrm{Na}\underline{\mathrm{B}}{\mathrm{H}}_4.$

Assign oxidation number to the underlined element in the following species:

${\mathrm{H}}_2{\underline{\mathrm{S}}}_2{\mathrm{O}}_7$.