Assign oxidation number to the underlined element in each of the following specie:

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

 What are the oxidation number of the underlined element in each of the following and how do you rationalise your result ?

${\mathrm{H}}_2{\underline{\mathrm{S}}}_4{\mathrm{O}}_6$.

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

${\underset{\_}{\mathrm{Fe}}}_3{\mathrm{O}}_4$.

 What are the oxidation number of the underlined element in each of the following and how do you rationalise your result ?

$\underline{\mathrm{C}}{\mathrm{H}}_3\underline{\mathrm{C}}{\mathrm{H}}_2\mathrm{OH}$.