Multiple choice What is the molecular formula of butane? C4H8 C4H9 C4H10 C5H12 Reveal answer Fill a bubble to check yourself C Correct answer Explanation Butane is a 4-carbon alkane with the formula C4H10 following the CnH2n+2 pattern for alkanes. Substituting n=4 gives C4H(2×4+2) = C4H10.