In a homologous series, members are represented by a general formula and show what?

• A. Similar properties and trends in physical properties
• B. Completely different properties
• C. Identical boiling points
• D. No general formula

Answer: (A)

In a homologous series, compounds share the same functional group and differ by one CH2 unit at a time, so they behave chemically in a similar way and show predictable trends in physical properties as the chain length changes. The general formula captures this pattern across the whole series, reflecting the repeating CH2 addition. For example, in alkanes the family formula is CnH2n+2, so methane, ethane, propane, and so on all have the same type of chemistry, and their boiling points rise gradually with increasing molecular size due to stronger van der Waals forces. This combination of shared chemical behavior and smooth physical-property trends is exactly what the statement describes. The other options don’t fit because properties aren’t completely different, boiling points aren’t identical, and there is a general formula that applies to the series.