Which pair of formulas represents the empirical formula and the molecular formula of a compound?

• A. CH4 and C2H4
• B. C2H4 and C2H2
• C. C2H2 and CH
• D. CH and C2H2

Answer: (D)

Verified step by step guidance

1. Understand the difference between empirical and molecular formulas: The empirical formula shows the simplest whole-number ratio of atoms in a compound, while the molecular formula shows the actual number of atoms of each element in a molecule.
2. Analyze each pair of formulas given to determine which one is the empirical formula and which one is the molecular formula by comparing their atom ratios.
3. For the pair CH and C2H2, check if CH is the simplest ratio of atoms and if C2H2 is a whole-number multiple of CH.
4. Confirm that CH has a 1:1 ratio of carbon to hydrogen atoms, which is the simplest ratio, making it the empirical formula.
5. Verify that C2H2 has twice the number of atoms as CH, indicating it is the molecular formula corresponding to the empirical formula CH.