Identify the correct statements from the following

i) Oxygen shows $-2,-1,+1,+2$ oxidation states.

ii) The thermal stability of ${\mathrm{H}}_2\mathrm{O},{\mathrm{H}}_2\mathrm{Se},{\mathrm{H}}_2\mathrm{ }\mathrm{S}$ follows the order ${\mathrm{H}}_2\mathrm{O}<{\mathrm{H}}_2\mathrm{ }\mathrm{S}<{\mathrm{H}}_2\mathrm{Se}$

iii) The reducing nature of ${\mathrm{H}}_2\mathrm{Se},{\mathrm{H}}_2\mathrm{ }\mathrm{S},{\mathrm{H}}_2\mathrm{Te}$ follows the order ${\mathrm{H}}_2\mathrm{ }\mathrm{S}<{\mathrm{H}}_2\mathrm{Se}<{\mathrm{H}}_2\mathrm{Te}$

 In oxygen family down the group thermal stability decreases order of thermal stability ${\mathrm{H}}_2\mathrm{ }\mathrm{S}<{\mathrm{H}}_2\mathrm{Se}<{\mathrm{H}}_2\mathrm{Te}$

The reason is because metal- hydrogen bond dissociation energy decrease down the group with the increase in the size of central atom.

Oxygen is considered to be the most electro negative element after fluorine. It shows mostly -2 oxidation states to form compounds, however it also shows $\text{(-1) Oxidation states (}{\mathrm{H}}_2{\mathrm{O}}_2\text{ ), }+1\text{ in }{\mathrm{O}}_2{ \mathrm{F}}_2\text{ and }+2\text{ in }{\mathrm{OF}}_2$. Thus Oxygen shows $-2,-1,+1,+2$ oxidation states.

The reducing nature of ${\mathrm{H}}_2\mathrm{Se},{\mathrm{H}}_2\mathrm{ }\mathrm{S},{\mathrm{H}}_2\mathrm{Te}$ follows the order ${\mathrm{H}}_2\mathrm{ }\mathrm{S}<{\mathrm{H}}_2\mathrm{Se}<{\mathrm{H}}_2\mathrm{Te}$.