Which of the following represents a polar covalent bond?

• A. H–Cl
• B. Cl–Cl
• C. Na–Cl
• D. O=O

Answer: (A)

Verified step by step guidance

1. Step 1: Understand the concept of bond polarity. A polar covalent bond occurs when two atoms share electrons unequally due to a difference in electronegativity between them.
2. Step 2: Identify the types of bonds in the options: H–Cl and Cl–Cl are covalent bonds, Na–Cl is an ionic bond, and O=O is a double covalent bond between identical atoms.
3. Step 3: Compare electronegativity values of the atoms involved. For H–Cl, hydrogen and chlorine have different electronegativities, leading to unequal sharing of electrons (polar covalent). For Cl–Cl and O=O, the atoms are identical, so the electrons are shared equally (nonpolar covalent).
4. Step 4: Recognize that Na–Cl involves a metal and a nonmetal, which typically forms an ionic bond rather than a covalent bond.
5. Step 5: Conclude that the bond with unequal sharing of electrons (polar covalent) is H–Cl, because it involves two different nonmetals with different electronegativities.