Question

The mass percent of carbon in pure acetone, C2H5OH is 52.1%. A chemist analyzes an impure sample of ethanol and determines that the mass percent of carbon is 49.5%. Which of the following impurities could account for the low mass percent of carbon in the sample?
(A) methanol, CH3OH
(B) acetone, C3H6O
(C) butanol, C4H9OH
(D) acetaldehyde,C2H4O

Answer 1

I'm not 100% on this but I would calculate the % carbon in each of the answer choices and see which one is lower than 52.% thus bringing the mass percent down