Which of the following species has a net dipole moment?

• A. BF_3
• B. CO
• C. CO_2
• D. CCl_4

Answer: (B)

Verified step by step guidance

1. Step 1: Understand what a net dipole moment is. A molecule has a net dipole moment if it has polar bonds arranged asymmetrically so that the individual bond dipoles do not cancel out, resulting in an overall molecular polarity.
2. Step 2: Analyze the molecular geometry and bond polarity of BF_3. BF_3 has a trigonal planar shape with three B-F bonds. Each B-F bond is polar due to the difference in electronegativity, but the symmetrical trigonal planar arrangement causes the bond dipoles to cancel out, resulting in no net dipole moment.
3. Step 3: Analyze CO_2. CO_2 is a linear molecule with two polar C=O bonds pointing in opposite directions. Because the molecule is linear and symmetrical, the bond dipoles cancel each other, so CO_2 has no net dipole moment.
4. Step 4: Analyze CCl_4. CCl_4 has a tetrahedral geometry with four polar C-Cl bonds. The symmetrical tetrahedral shape causes the bond dipoles to cancel out, so CCl_4 has no net dipole moment.
5. Step 5: Analyze CO. CO is a diatomic molecule with a polar bond due to the difference in electronegativity between carbon and oxygen. Since it is a diatomic molecule, the bond dipole cannot be canceled out, so CO has a net dipole moment.