Which of the following is a molecular compound?

• A. MgO
• B. NaCl
• C. KBr
• D. CO_2

Answer: (D)

Verified step by step guidance

1. Understand the difference between ionic and molecular compounds: Ionic compounds are formed between metals and nonmetals and consist of ions, while molecular compounds are formed between nonmetals and consist of molecules sharing electrons through covalent bonds.
2. Identify the elements in each compound: MgO contains magnesium (a metal) and oxygen (a nonmetal), NaCl contains sodium (a metal) and chlorine (a nonmetal), KBr contains potassium (a metal) and bromine (a nonmetal), and CO_2 contains carbon and oxygen, both nonmetals.
3. Classify each compound based on the elements involved: Since MgO, NaCl, and KBr all contain metals and nonmetals, they are ionic compounds. CO_2, containing only nonmetals, is a molecular compound.
4. Recall that molecular compounds typically have covalent bonds formed by sharing electrons between nonmetal atoms, which is the case for CO_2.
5. Conclude that among the given options, CO_2 is the molecular compound because it consists solely of nonmetals bonded covalently.