What is the molecular formula for ethanol?

• A. C2H5OH
• B. C2H6O
• C. C3H7OH
• D. C2H5O2

Answer: (A)

Two carbons, six hydrogens, and one oxygen make up ethanol. Writing the formula as C2H5OH keeps those counts intact while explicitly showing the hydroxyl group (the OH) attached to the carbon framework. This presentation is a common shorthand in organic chemistry because it communicates not just composition but also the functional group present. While C2H6O conveys the same overall composition, C2H5OH emphasizes the alcohol group, which is why it’s a preferred way to represent ethanol in many contexts. The other options would imply a different molecule (more carbons or more oxygens), so they don’t fit ethanol.