Which of the following statements about functional groups is true?

• A. Functional groups do not affect the physical properties of a compound.
• B. Functional groups determine the chemical reactivity and properties of organic molecules.
• C. Functional groups are always found at the end of a carbon chain.
• D. All functional groups contain only carbon and hydrogen atoms.

Answer: (B)

Verified step by step guidance

1. Understand what a functional group is: a specific group of atoms within molecules that is responsible for the characteristic chemical reactions of those molecules.
2. Recall that functional groups influence both the chemical reactivity and physical properties (like boiling point, solubility) of organic compounds, so the statement that they do not affect physical properties is false.
3. Recognize that functional groups are not restricted to the ends of carbon chains; they can be located anywhere within the molecule, so the statement about their position is false.
4. Know that functional groups often contain atoms other than carbon and hydrogen, such as oxygen, nitrogen, sulfur, or halogens, so the statement that all functional groups contain only carbon and hydrogen is false.
5. Conclude that the true statement is that functional groups determine the chemical reactivity and properties of organic molecules, as this aligns with their fundamental role in organic chemistry.