What is the percent mass oxygen in acetone

27.6 %.

Explanation:

Acetone has  the molecular formula (C₃H₆O).The molar mass of acetone is the summation of the atomic mass of the elements forming it multiplied by its number of atoms.

Atomic mass of C = 12.011 g/mol.

Atomic mass of H = 1.008 g/mol.

Atomic mass of O = 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.

∴ The mass % of O = (Atomic mass of O / molar mass of acetone) x 100 = [(15.999 g/mol) / (58.08 g/mol)] = 27.6 %.

Forgot the question hahaha