Final answer:
The molecular formula of the compound with an empirical formula of CH₂O and a molar mass of 90 g/mol is C₃H₆O₃, three times the empirical formula.
Step-by-step explanation:
The empirical formula represents the simplest whole-number ratio of the elements in a compound, while the molecular formula shows the actual number of atoms of each element in a molecule. To determine the molecular formula from the empirical formula, we need to know the molar mass of the compound.
Given the empirical formula CH₂O and the molar mass of the compound as 90 g/mol, we can calculate that the molecular formula is C₃H₆O₃. This is because the molar mass of the empirical formula (CH₂O) is 30 g/mol (12 for carbon, 2 for hydrogen, and 16 for oxygen), and 90 g/mol is three times that amount. Therefore, the molecular formula of the compound is three times the empirical formula.