AP Chemistryhardmcq1 pt
A compound is 92.3% carbon and 7.7% hydrogen by mass with a molar mass of 78 g/mol. What is its molecular formula?
A.C₆H₆
B.CH
C.C₂H₂
D.C₆H₁₂
Explanation
Core Concept
Assume 100 g: C = 92.3/12.01 = 7.69 mol, H = 7.7/1.008 = 7.64 mol — ratio 1:1, so empirical formula CH (13.02 g/mol). 78/13.02 = 6, giving C₆H₆ (benzene).
Correct Answer
AC₆H₆
More Unit 1: Atomic Structure and Properties practice questions
- mediumWhy does atomic radius decrease across a period from Li to F?
- easyWhich element has the largest atomic radius: S, Se, or Te?
- easyWhich orbital diagram for carbon's 2p subshell is correct (arrows represent electrons)?
- mediumA 34.0 g sample of NH₃ contains how many moles of hydrogen atoms?
- mediumHow many atoms are in 9.0 g of water (molar mass 18.0 g/mol)?
Practice more AP Chemistry questions with full explanations
Practice Unit 1: Atomic Structure and Properties Questions →