A compound contains, by mass, 40.0% carbon, 6.71% hydrogen, and 53.3% oxygen. A 0.320 mole sample of this compound weighs 28.8 g. The molecular formula of this compound is C₃H₆O₃.

The correct answer is 'True'.

A 0.320 mole sample of this compound weighs 28.8 g. Mass of one mole of the compound is 90. The compound contains, by mass, 40.0% carbon, 6.71% hydrogen, and 53.3% oxygen.
40% of 90g = 36g, hence 3 carbon atoms as atomic mass of carbon is 12g.
6.71% of 90 = 6.039g, hence 6 hydrogen atoms as atomic mass of hydrogen is 1g.
53.3% of 90 = 47.97  48g, hence 3 oxygen atoms as atomic mass of oxygen is 16g.
The molecular formula of this compound is C₃H₆O₃.