Which of the following compounds is formed primarily through covalent bonding?

• A. H2O
• B. MgCl2
• C. NaCl
• D. CaO

Answer: (A)

Verified step by step guidance

1. Understand the types of chemical bonds: Covalent bonds involve the sharing of electrons between atoms, typically between nonmetals. Ionic bonds involve the transfer of electrons from one atom to another, typically between metals and nonmetals.
2. Identify the elements in each compound: H2O consists of hydrogen (H) and oxygen (O), both nonmetals. MgCl2 consists of magnesium (Mg), a metal, and chlorine (Cl), a nonmetal. NaCl consists of sodium (Na), a metal, and chlorine (Cl), a nonmetal. CaO consists of calcium (Ca), a metal, and oxygen (O), a nonmetal.
3. Determine the type of bonding in each compound: H2O is formed by covalent bonds because it involves nonmetals sharing electrons. MgCl2, NaCl, and CaO are formed by ionic bonds because they involve metals transferring electrons to nonmetals.
4. Recognize that covalent bonds are typically found in compounds formed by nonmetals, while ionic bonds are found in compounds formed by metals and nonmetals.
5. Conclude that H2O is the compound formed primarily through covalent bonding, as it consists of nonmetals sharing electrons.