Step 1: Identify the molecular formula C2H5-CHO. This shows that the compound has two carbon atoms (C2) and a functional group (CHO) that indicates it is an aldehyde.
Step 2: Recognize that aldehydes are named based on the longest carbon chain that includes the carbonyl group (C=O). In this case, the longest chain has two carbon atoms.
Step 3: The base name for a two-carbon aldehyde is derived from 'ethane', which is the alkane with two carbons.
Step 4: Change the suffix 'ane' in 'ethane' to 'al' to indicate that it is an aldehyde. This gives us 'ethanal'.
Step 5: Conclude that the IUPAC name for the compound C2H5-CHO is Ethanal.
