Properties of Homologous Series

Steps:

• Homologous series consist of organic compounds with the same functional group and successive members differing by -CH2-.
• Statement 1 is false: series like alkenes are unsaturated, not all contain only saturated compounds.
• Statement 2 is false: reactivity varies; alkanes in a series are generally unreactive.
• Statement 3 is true: each series follows a general formula, e.g., CnH2n+2 for alkanes.
• Statement 4 is true: physical properties like boiling point increase gradually with molecular size.

Why D is correct:

• D selects statements 3 and 4, matching the definition of homologous series as having a general formula and gradual physical property changes.

Why the others are wrong:

• A includes false statements 1 and 2.
• B includes false statements 1 and 2.
• C includes false statement 1.

Final answer: D