• # question_answer 56) ${{\text{P}}_{2}}{{O}_{5}}$is an anhydride of A) $HP{{O}_{3}}$                  B) ${{H}_{3}}P{{O}_{4}}$C) ${{H}_{2}}{{P}_{2}}{{O}_{7}}$                      D) ${{H}_{3}}P{{O}_{3}}$

The oxidation number of central atom in its anhydrate and acid is same. In ${{P}_{2}}{{O}_{5}},$let the oxidation number of$P=x.$ $2x-10=0$ In ${{H}_{3}}P{{O}_{4}},$let the oxidation number of P = y. $3+y-8=0$ $y=+\,5$ As oxidation number of P in${{P}_{2}}{{O}_{5}}$and ${{H}_{3}}P{{O}_{4}}$is same, So${{P}_{2}}{{O}_{5}}$is an anhydride of ${{H}_{3}}P{{O}_{4}}.$ Hence, the correct option is [b].