Question

The oxidation number of underlined element in $K_4{\underset{–}{P}}_2{O}_7$ compound is :

• A. 5
• B. -5
• C. 3
• D. None of these

Answer 1

The correct option is A 5

Let $x$ be the oxidation number of P in $K_4{\underset{–}{P}}_2{O}_7$.
Since, the overall charge on the complex is $0$, the sum of oxidation states of all elements in it should be equal to $0$.
$4(+1)+2x+7(2-)=0$
$4+2x-14=0$
$x=+5$
Thus, the oxidation number of P in $K_4{\underset{–}{P}}_2{O}_7$ is $+5$.

Hence, the correct option is A.