An herbicide is found to contain only C, H, N, and Cl. The complete combustion of a 100.0-mg sample of the herbicide in excess oxygen produces 83.16 mL of CO₂ and 73.30 mL of H₂O vapor expressed at STP. A separate analysis shows that the sample also contains 16.44 mg of Cl. (c) What other information would you need to know about this compound to calculate its true molecular formula?