Which option shows the displayed formula for propane?

• A. CH3-CH2-CH3
• B. CH3-CH2-CH2-CH3
• C. C3H8
• D. CH4

Answer: (A)

Propane is a three-carbon alkane with only single bonds, so its displayed structural formula shows three carbon atoms in a row with hydrogens filling the remaining bonds: CH3-CH2-CH3. This arrangement matches propane’s three-carbon chain and the typical hydrogen count for a saturated hydrocarbon. The other options depict different ideas: CH3-CH2-CH2-CH3 shows four carbons (butane), C3H8 gives the same molecule in formula form but not its structure, and CH4 is methane, a one-carbon molecule. So the displayed formula for propane is CH3-CH2-CH3.