Which of the following compounds most likely contains polar covalent bonds?

• A. AlF_3
• B. Br_2
• C. NF_3
• D. NaCl

Answer: (C)

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: Analyze each compound's bonding type by considering the elements involved and their electronegativity differences. Large differences often lead to ionic bonds, small or moderate differences lead to polar covalent bonds, and very small or zero differences lead to nonpolar covalent bonds.
3. Step 3: For AlF_3, aluminum and fluorine have a large electronegativity difference, so the bonds are mostly ionic rather than polar covalent.
4. Step 4: For Br_2, both atoms are the same element, so the bond is nonpolar covalent because electrons are shared equally.
5. Step 5: For NF_3, nitrogen and fluorine have a moderate electronegativity difference, resulting in polar covalent bonds. For NaCl, the difference is very large, so the bond is ionic.