A) Mr(P2O5) = Mr = 2Ar(P) + 5Ar(O) = 2 * 31 + 5 * 16 = 142
w(P) = 2Ar(P) / Mr = 62 / 142 = 0.4366 = 43.66%
B) Mr(H3PO3) = Mr = 3Ar(H) + Ar(P) + 3Ar(O) = 3 * 1 + 31 + 3 * 16 = 82
w(P) = Ar(P) / Mr = 31 / 82 = 0.378 = 37.8%
C) Mr(P2O3) = Mr = 2Ar(P) + 3Ar(O) = 2 * 31 + 3 * 16 = 110
w(P) = 2Ar(P) / Mr = 62 / 110 = 0.5636 = 56.36%
D) Mr(H3PO4) = Mr = 3Ar(H) + Ar(P) + 4Ar(O) = 3 * 1 + 31 + 4 * 16 = 98
w(P) = Ar(P) / Mr = 31 / 98 = 0.3162 = 31.62%
E) Mr(Ca3(PO4)2) = Mr = 3Ar(Ca) + 2Ar(P) + 8Ar(O) = 3 * 40 + 2 * 31 + 8 * 16 = 310
w(P) = 2Ar(P) / Mr = 62 / 310 = 0.2 = 20%
Ответ: E < D < B < A < C