Which of the following molecules has an approximate bond angle of 109.5°?

• A. CO2
• B. BF3
• C. CH4
• D. NH3

Answer: (C)

Verified step by step guidance

1. Identify the molecular geometry of each molecule listed: CO2, BF3, CH4, and NH3. The bond angle depends on the shape of the molecule, which is determined by the arrangement of electron pairs around the central atom.
2. Recall that a bond angle of approximately 109.5° corresponds to a tetrahedral geometry, which occurs when there are four regions of electron density (bonding pairs) around the central atom.
3. Analyze CO2: It has a linear shape with two double bonds and no lone pairs on the central atom, resulting in a bond angle of 180°.
4. Analyze BF3: It has three bonding pairs and no lone pairs on the central atom, resulting in a trigonal planar shape with bond angles of about 120°.
5. Analyze CH4: It has four bonding pairs and no lone pairs on the central atom, resulting in a tetrahedral shape with bond angles close to 109.5°. NH3 has a trigonal pyramidal shape with bond angles slightly less than 109.5° due to the lone pair repulsion.