Which of the following molecules has bond angles slightly less than 120°?

• A. BF3
• B. NO3-
• C. CO2
• D. SO2

Answer: (D)

Verified step by step guidance

1. Identify the molecular geometry of each molecule or ion listed. For example, BF3 and NO3- both have trigonal planar geometries, CO2 is linear, and SO2 has a bent (or V-shaped) geometry.
2. Recall that ideal bond angles for trigonal planar molecules are exactly 120°, and for linear molecules, the bond angle is 180°.
3. Understand that molecules with lone pairs on the central atom, like SO2, experience lone pair-bond pair repulsions that reduce bond angles slightly from the ideal values.
4. Recognize that SO2 has a bent shape due to one lone pair on sulfur, which compresses the bond angle to slightly less than 120°, unlike BF3 and NO3- which have no lone pairs on the central atom and maintain bond angles close to 120°.
5. Conclude that the molecule with bond angles slightly less than 120° is SO2 because of its bent geometry caused by lone pair repulsion.