Which of the following molecules is most likely to exhibit a deviation from its idealized bond angle?

• A. CO2 (carbon dioxide)
• B. BF3 (boron trifluoride)
• C. NH3 (ammonia)
• D. CH4 (methane)

Answer: (C)

Verified step by step guidance

1. Identify the idealized bond angles for each molecule based on their electron pair geometry using VSEPR theory: CO2 is linear with 180°, BF3 is trigonal planar with 120°, NH3 is trigonal pyramidal with approximately 107°, and CH4 is tetrahedral with 109.5°.
2. Recognize that deviations from ideal bond angles occur when there are lone pairs on the central atom because lone pairs repel bonding pairs more strongly, causing bond angles to adjust.
3. Examine each molecule's central atom for lone pairs: CO2 has no lone pairs on carbon, BF3 has no lone pairs on boron, NH3 has one lone pair on nitrogen, and CH4 has no lone pairs on carbon.
4. Understand that NH3, with one lone pair, will have bond angles slightly less than the ideal tetrahedral angle (109.5°) due to increased lone pair-bond pair repulsion, causing deviation.
5. Conclude that NH3 is most likely to exhibit a deviation from its idealized bond angle because of the presence of a lone pair on the central atom affecting the molecular geometry.