Empirical formula simplifies molecular formula to lowest ratio Steps:

• Define empirical formula as simplest whole-number ratio of atoms; molecular formula as actual atom count.
• For each compound, derive empirical formula by dividing subscripts by greatest common divisor.
• Compare empirical to given molecular formula for differences.
• Select compound where they differ.

Why B is correct:

• H2O2 molecular formula simplifies to HO empirical (divide by 2), differing from actual structure.

Why the others are wrong:

• A: C4H9OH (or C4H10O) already simplest ratio, so empirical matches molecular.
• C: NO2 subscripts (1:2) have no common divisor >1, so empirical matches molecular.
• D: H2O subscripts (2:1) already simplest, so empirical matches molecular.

Final answer: B