Question

In $H_2{P}_2{O}_7$ , what is the oxidation number of $P$ ?

Answer 1

Answer: 6

$\left[\begin{array}{ccc}+1& x& -2\\ H_2& P_2& O_7\end{array}\right]$
$\therefore (+1\times 2)+(2x)+(-2\times 7)=0$
or $x=+6$