Question

Oxidation number of P in $M{g}_2{P}_2{O}_7$ is?

• A. $+3$
• B. $+2$
• C. $+5$
• D. $-3$

Answer 1

The correct option is C $+5$

Let the oxidation number of $P$ in ${Mg}_2{P}_2{O}_7$ be $x$. The oxidation states of $Mg$ and $O$ are +2 and -2 respectively. Since the atom as whole is neutral, following equation holds true:

$2\times (+2)+2\times \left(x\right)+7\times (-2)=0⟹4+2x-14=0⟹2x=14-4⟹2x=10⟹x=\frac{10}{2}=5$

Hence, answer is C.