What is the correct formula for propane?

Propane is an alkane with three carbon atoms, which corresponds to the chemical formula C₃H₈. The structural representation of propane can be expressed as CH₃CH₂CH₃, demonstrating a straight-chain alkane where the first carbon is bonded to three hydrogen atoms, the second carbon is bonded to two hydrogen atoms, and the third carbon is also bonded to three hydrogen atoms.

In the context of the options provided, CH₃CH₂CH₃ accurately reflects this structure, indicating a three-carbon chain with the respective number of hydrogen atoms attached to each carbon. This helps illustrate the molecular structure of propane, confirming its designation as a three-carbon alkane.

The other formulas do not represent propane. For instance, CH₄ indicates methane, the simplest alkane with one carbon atom. CH₃CH₃ denotes ethane, which consists of two carbon atoms. Meanwhile, CH₃CH₂CH₂CH₃ represents butane, an alkane with four carbon atoms. Thus, only the formula CH₃CH₂CH₃ distinctly identifies propane among the options.