Which of the following statements correctly describes the molecular formula?

What is the primary difference between a molecular formula and an empirical formula?

Given the following mass percentages: 40% carbon, 6.7% hydrogen, and 53.3% oxygen, what is the empirical formula of the compound?

A compound has an empirical formula of CH and a molar mass of 78 g/mol. Determine the n factor and the molecular formula.

A compound contains 70% iron and 30% oxygen by mass. What is the empirical formula?