Which of the following statements is NOT true about molecular compounds?

• A. They conduct electricity well in aqueous solution.
• B. They generally have low melting and boiling points compared to ionic compounds.
• C. They are typically formed from two or more nonmetal elements.
• D. They are held together by covalent bonds.

Answer: (A)

Verified step by step guidance

1. Step 1: Understand what molecular compounds are. Molecular compounds are formed when two or more nonmetal atoms share electrons through covalent bonds.
2. Step 2: Recall the properties of molecular compounds. They generally have low melting and boiling points because the forces between molecules (intermolecular forces) are weaker than ionic bonds.
3. Step 3: Consider electrical conductivity. Molecular compounds usually do not conduct electricity well in aqueous solution because they do not produce ions when dissolved; unlike ionic compounds, they do not dissociate into charged particles.
4. Step 4: Analyze each statement given: (a) They conduct electricity well in aqueous solution — this is generally false for molecular compounds; (b) They generally have low melting and boiling points compared to ionic compounds — true; (c) They are typically formed from two or more nonmetal elements — true; (d) They are held together by covalent bonds — true.
5. Step 5: Conclude that the statement 'They conduct electricity well in aqueous solution' is NOT true about molecular compounds, making it the correct choice for the question.