Answer:
Mn(NO3)3 Molar mass = (54.93) + (3 x 14) + (9 x 16) = 240.93g/mol
Total number of Oxygen atoms in formula = 9
Total mass of oxygen atoms theoretically in the formula = 9x16 = 144g/mol
Oxygen's percentage composition:
(144/240.93) x 100 = 59.7% of the compound is oxygen
