Answer: C - 27.6%.
Acetone has the molecular formula (C₃H₆O). In chemistry, the molar mass of a chemical compound is defined as the mass of a sample of the compound divided by the amount of substance in that sample, as measured in moles.[
Atomic mass of Carbon = 12.011 g/mol.
Atomic mass of Hydrogen = 1.008 g/mol.
Atomic mass of Oxygen = 15.999 g/mol.
The molar mass of acetone = [(3 x atomic mass of C) + (6 x atomic mass of H) + (Atomic mass of O)] = [(3 x 12.011 g/mol) + (6x 1.008 g/mol) + (15.999 g/mol)] = 58.08 g/mol.
The mass % of any element = [(no, of the element atoms x atomic mass of the element) / molar mass of the compound] x 100.
Thus the mass % of O = (Atomic mass of O / molar mass of acetone) x 100 = [(15.999 g/mol) / (58.08 g/mol)] is equal to 7.6 %.
