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?

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

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

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

Justify that the following reaction are redox reaction:

${\mathrm{CuO}}_{\left(\mathrm{s}\right)} + {\mathrm{H}}_{2\left(\mathrm{g}\right)} \to {\mathrm{Cu}}_{\left(\mathrm{s}\right)} + {\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{g}\right)}$

Justify that the following reaction are redox reaction:

${\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)+ 3\mathrm{CO}\left(\mathrm{g}\right) \to 2\mathrm{Fe}\left(\mathrm{s}\right)+ 3{\mathrm{CO}}_2\left(\mathrm{g}\right)$.

Justify that the following reaction are redox reaction:

$4{\mathrm{BCl}}_{3\left(\mathrm{g}\right)} + 3{\mathrm{LiAlH}}_{4\left(\mathrm{s}\right)} \to 2{\mathrm{B}}_2{\mathrm{H}}_{6\left(\mathrm{g}\right)} + 3{\mathrm{LiCl}}_{\left(\mathrm{s}\right)} + 3 {\mathrm{AlCl}}_{3\left(\mathrm{s}\right)}$

$2\mathrm{K}\left(\mathrm{s}\right)+ {\mathrm{F}}_2\left(\mathrm{g}\right)\to 2{\mathrm{K}}^{+}{\mathrm{F}}^{-}\left(\mathrm{s}\right)$.

$4{\mathrm{NH}}_3\left(\mathrm{g}\right)+ 5{\mathrm{O}}_2\left(\mathrm{g}\right)\to 4\mathrm{NO}\left(\mathrm{g}\right)+6{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$.