Science, Tech, Math › Science Molecular Formula Practice Test Questions Print MicrovOne / Getty Images Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. Learn about our Editorial Process Updated on August 01, 2019 The molecular formula of a compound is a representation of the number and type of elements present in one molecular unit of the compound. This 10-question practice test deals with finding the molecular formula of chemical compounds. A periodic table will be required to complete this test. Answers appear after the final question. Question 1 An unknown compound is found to contain 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen with a molecular mass of 60.0 g/mol. What is the molecular formula of the unknown compound? Question 2 A hydrocarbon is a compound comprised of carbon and hydrogen atoms. An unknown hydrocarbon is found to contain 85.7% carbon and an atomic mass of 84.0 g/mol. What is its molecular formula? Question 3 A piece of iron ore is found to contain a compound containing 72.3% iron and 27.7% oxygen with a molecular mass of 231.4 g/mol. What is the molecular formula of the compound? Read More Chemical Formulas Practice Test Questions By Todd Helmenstine Question 4 A compound containing 40.0% carbon, 5.7% hydrogen, and 53.3% oxygen has an atomic mass of 175 g/mol. What is the molecular formula? Question 5 A compound contains 87.4% nitrogen and 12.6% hydrogen. If the molecular mass of the compound is 32.05 g/mol, what is the molecular formula? Question 6 A compound with a molecular mass of 60.0 g/mol is found to contain 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen. What is the molecular formula? Question 7 A compound with molecular mass of 74.1 g/mol is found to contain 64.8% carbon, 13.5% hydrogen, and 21.7% oxygen. What is the molecular formula? Question 8 A compound is found to contain 24.8% carbon, 2.0% hydrogen, and 73.2% chlorine with a molecular mass of 96.9 g/mol. What is the molecular formula? Question 9 A compound contains 46.7% nitrogen and 53.3% oxygen. If the molecular mass of the compound is 60.0 g/mol, what is the molecular formula? Question 10 A gas sample is found to contain 39.10% carbon, 7.67% hydrogen, 26.11% oxygen, 16.82% phosphorus, and 10.30% fluorine. If the molecular mass is 184.1 g/mol, what is the molecular formula? Answers 1. C2H4O22. C6H123. Fe3O44. C6H12O65. N2H46. C2H4O27. C4H10O8. C2H2Cl29. N2O210. C6H14O3PF Cite this Article Format mla apa chicago Your Citation Helmenstine, Anne Marie, Ph.D. "Molecular Formula Practice Test Questions." ThoughtCo, Aug. 28, 2020, thoughtco.com/molecular-formula-practice-test-questions-604125. Helmenstine, Anne Marie, Ph.D. (2020, August 28). Molecular Formula Practice Test Questions. Retrieved from https://www.thoughtco.com/molecular-formula-practice-test-questions-604125 Helmenstine, Anne Marie, Ph.D. "Molecular Formula Practice Test Questions." ThoughtCo. https://www.thoughtco.com/molecular-formula-practice-test-questions-604125 (accessed April 19, 2024). copy citation