Question

select the correct answer. which property is typical of a covalent compound? a. they are extremely hard solids. b. they have low melting and boiling points. c. they conduct electricity. d. they have rigid crystal structures. e. they exist only as gases and liquids.

Explanation:

To determine the property typical of covalent compounds, we analyze each option:

• Option A: Extremely hard solids are typical of ionic or network covalent (e.g., diamond) compounds, but most covalent compounds are not extremely hard. So A is incorrect.
• Option B: Covalent compounds (molecular) have weak intermolecular forces, leading to low melting/boiling points. This matches their typical properties.
• Option C: Covalent compounds (except in aqueous/ionic form) do not conduct electricity, as they lack free ions/electrons. So C is incorrect.
• Option D: Rigid crystal structures are typical of ionic or network solids, not most molecular covalent compounds. So D is incorrect.
• Option E: Many covalent compounds exist as solids (e.g., sugar, wax), so “only gases/liquids” is false.

Answer:

B. They have low melting and boiling points.