What is the value of $$x$$ in order to balance following redox reaction?

$$\mathrm{Mn}_{(\mathrm{aq})}^{2+}+x \mathrm{ClO}_{3(\mathrm{aq})}^{-} \rightarrow \mathrm{MnO}_{2(\mathrm{~s})}+x \mathrm{ClO}_{2(\mathrm{aq})}$$

What is the oxidation state of carbon in $$\mathrm{CaC}_2$$ and $$\mathrm{K}_2 \mathrm{C}_2 \mathrm{O}_4$$ respectively?

Which one of the following conversions does NOT involve either oxidation or reduction?

Identify reducing agent in following reaction

$$\mathrm{H}_2 \mathrm{O}_{2(\mathrm{ag})}+\mathrm{ClO}_{4(\mathrm{aq})}^{-} \rightarrow \mathrm{ClO}_{2(\mathrm{aq})}^{-}+\mathrm{O}_{2(\mathrm{g})}$$