With reference to the redox properties of hydrogen peroxide $\left(\mathrm{H}_2 \mathrm{O}_2\right)$, which of these reactions are feasible?

(i) $2 \mathrm{Fe}^{2+} 2 \mathrm{H}^{+}+\mathrm{H}_2 \mathrm{O}_2 \longrightarrow 2 \mathrm{Fe}^{3+}+2 \mathrm{H}_2 \mathrm{O}$

(ii) $2 \mathrm{MnO}_4^{-}+6 \mathrm{H}^{+}+5 \mathrm{H}_2 \mathrm{O}_2 \longrightarrow 2 \mathrm{Mn}^{2+}+8 \mathrm{H}_2 \mathrm{O}+5 \mathrm{O}_2$

(iii) $2 \mathrm{Fe}^{2+}+\mathrm{H}_2 \mathrm{O}_2 \longrightarrow 2 \mathrm{Fe}^{3+}+2 \mathrm{OH}^{-}$

(iv) $2 \mathrm{MnO}_4^{-}+3 \mathrm{H}_2 \mathrm{O}_2 \longrightarrow 2 \mathrm{MnO}_2+2 \mathrm{H}_2 \mathrm{O} +3 \mathrm{O}_2+2 \mathrm{OH}^{-} $

Which among the following is/are primary component(s) of the synthesis gas?

What is the $\%$ strength of 22.4 volume of $\mathrm{H}_2 \mathrm{O}_2$ solution?

Hard water contains ion of