\({H}_{4} {P}_{2} {O}_{7}\)
\(2 {x}+4(+1)+7(-2)=0\)
\({x}=+5\)
\({H}_{4} {P}_{2} {O}_{5}\)
\(2 {x}+4(+1)+5(-2)=0\)
\({x}=+3\)
\({H}_{4} {P}_{2} {O}_{6}\)
\(2 {x}+4(+1)+6(-2)=0\)
\({x}=+4\)
$ 3 \mathrm{ROH}+\mathrm{PCl}_3 \rightarrow 3 \mathrm{RCl}+\mathrm{A} $
$ \mathrm{ROH}+\mathrm{PCl}_5 \rightarrow \mathrm{RCl}+\mathrm{HCl}+\mathrm{B}$