Which of the following is the displayed formula for methane?

• A. CH4
• B. C2H6
• C. C3H8
• D. C4H10

Answer: (A)

Methane is the simplest alkane, so its formula must reflect one carbon atom bonded to four hydrogens. Carbon forms four bonds, and in methane all four are to hydrogen, giving the molecular formula CH4. The displayed formula should show one carbon center with four hydrogen atoms around it, which matches CH4. The other options correspond to larger alkanes with more carbon atoms: ethane has two carbons and six hydrogens, propane has three carbons and eight hydrogens, and butane has four carbons and ten hydrogens. In general, alkanes follow the formula CnH2n+2, and for methane (n = 1) that gives CH4, which aligns with the correct displayed formula.