What do methanol (CH2O), ethanoic acid (C2H4O2), and glucose (C3H6O3) all have in common?
a. They are all carbohydrates
b. They all have the same empirical formula
c. They all have the same % composition
d. All of the above are true

d

Explanation:

Carbohydrates are compounds containing carbon, hydrogen, and oxygen. Therefore, a is true.

An empirical formula is the simplest ratio of atoms present in a compound. Therefore, C2H4O2 and C3H6O3, (if you simplified them like you would a fraction) would be CH2O. Therefore b is correct,

They also have the same % composition, with a ratio of 1 carbon : 2 hydrogen : 1 oxygen. Therefore, c is correct.

Since a, b and c are all correct, the answer is d, all of the above are true.