Which one of the following compounds is considered to be an ionic compound?

• A. H_2O
• B. CO_2
• C. NaCl
• D. CH_4

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the difference between ionic and covalent compounds. Ionic compounds are formed by the transfer of electrons between metals and nonmetals, resulting in positive and negative ions held together by electrostatic forces. Covalent compounds involve the sharing of electrons between nonmetals.
2. Step 2: Identify the elements in each compound and classify them as metals or nonmetals. For example, NaCl consists of sodium (Na), a metal, and chlorine (Cl), a nonmetal.
3. Step 3: Analyze each compound: H_2O (hydrogen and oxygen) and CO_2 (carbon and oxygen) are composed only of nonmetals, so they form covalent bonds. CH_4 (carbon and hydrogen) also consists of nonmetals, forming covalent bonds.
4. Step 4: Recognize that NaCl is composed of a metal (Na) and a nonmetal (Cl), which typically form ionic bonds due to electron transfer from metal to nonmetal.
5. Step 5: Conclude that among the given compounds, NaCl is the ionic compound because it contains a metal and a nonmetal forming ions, while the others are covalent compounds.