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 element in the following species:

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

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

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

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

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

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

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

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

$\mathrm{KAl}{\left(\underline{\mathrm{S}}{\mathrm{O}}_4\right)}_2.12{\mathrm{H}}_2\mathrm{O}$

What is the oxidation number of the underlined element and how do you rationalise your result?
$\mathrm{K}{\underset{\_}{\mathrm{I}}}_3$

What is the oxidation number of the underlined element and how do you rationalize your result?

${\mathrm{H}}_2{\underset{\_}{\mathrm{S}}}_4{\mathrm{O}}_6$