Question

Oxidation number of P in $P_2{O}_7^{4-}$ is :

• A. 3
• B. 4
• C. 5
• D. 6

Answer 1

The correct option is C 5

Let the oxidation number of P in $P_2{O}_7^{4-}$ be $x$.
Since, the overall charge on complex is $-4$, sum of oxidation states of all elements in it should be equal to $-4$.
Hence, $2x+7(-2)=-4$
or, $x=+5$