**Q. What is the oxidation number of oxygen in H _{2}O_{2} ?**

Ans: Let us consider the oxidation number of oxygen in **H _{2}O_{2}** to be

**x.**

Also, we know that the oxidation number of Hydrogen is** +1.**

(+1) × 2 + (x) × 2 = 0

+2 +2x = 0

**x = -1 **

**Hence The oxidation number of oxygen in Hydrogen Peroxide is -1.**