(a) Nitrous oxide, N2O: 36.36% N, 63.64% O
(b) Silver thiosulfate, Ag2S2O3: 47.41% Ag, 13.46% S, 39.13% O
(c) Strontium ion in Sr3(PO4)2: 58.05% Sr .
(a) Nitrous oxide, N2O
Molar mass of N2O = 14.008 g/mol + 15.9994 g/mol = 29.9974 g/mol
Mass of N in 1 mol N2O = 2 * 14.008 g/mol = 28.016 g/mol
Percent composition of N = (28.016 g/mol / 29.9974 g/mol) * 100% = 93.636%
Mass of O in 1 mol N2O = 15.9994 g/mol
Percent composition of O = (15.9994 g/mol / 29.9974 g/mol) * 100% = 53.364%
(b) Silver thiosulfate, Ag2S2O3
Molar mass of Ag2S2O3 = 2 * 107.8682 g/mol + 2 * 32.065 g/mol + 3 * 15.9994 g/mol = 311.8089 g/mol
Mass of Ag in 1 mol Ag2S2O3 = 2 * 107.8682 g/mol = 215.7364 g/mol
Percent composition of Ag = (215.7364 g/mol / 311.8089 g/mol) * 100% = 69.209%
Mass of S in 1 mol Ag2S2O3 = 2 * 32.065 g/mol = 64.13 g/mol
Percent composition of S = (64.13 g/mol / 311.8089 g/mol) * 100% = 20.565%
Mass of O in 1 mol Ag2S2O3 = 3 * 15.9994 g/mol = 47.9982 g/mol
Percent composition of O = (47.9982 g/mol / 311.8089 g/mol) * 100% = 15.406%
(c) Strontium ion in Sr3(PO4)2
Molar mass of Sr3(PO4)2 = 3 * 87.62 g/mol + 2 * 30.973762 g/mol + 8 * 15.9994 g/mol = 603.91 g/mol
Mass of Sr in 1 mol Sr3(PO4)2 = 3 * 87.62 g/mol = 262.86 g/mol
Percent composition of Sr = (262.86 g/mol / 603.91 g/mol) * 100% = 43.571%