Which of the following substances should be classified as a molecular compound?

• A. HBr
• B. CO
• C. NaCl
• D. KBr

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the difference between molecular compounds and ionic compounds. Molecular compounds are formed by the sharing of electrons between nonmetal atoms, resulting in covalent bonds. Ionic compounds are formed by the transfer of electrons between metals and nonmetals, resulting in ionic bonds.
2. Step 2: Identify the elements in each substance and determine if they are metals or nonmetals. For example, HBr consists of hydrogen (a nonmetal) and bromine (a nonmetal), CO consists of carbon (a nonmetal) and oxygen (a nonmetal), NaCl consists of sodium (a metal) and chlorine (a nonmetal), and KBr consists of potassium (a metal) and bromine (a nonmetal).
3. Step 3: Classify each substance based on the types of elements involved. Substances composed only of nonmetals are typically molecular compounds, while those containing metals and nonmetals are ionic compounds.
4. Step 4: Conclude that HBr and CO are molecular compounds because they consist of only nonmetals bonded covalently, whereas NaCl and KBr are ionic compounds because they contain metals bonded ionically to nonmetals.
5. Step 5: Summarize that molecular compounds are characterized by covalent bonding between nonmetal atoms, which is the case for HBr and CO in this problem.