In which of the following liquids do the intermolecular forces include dipole-dipole forces?

• A. CH4 (methane)
• B. CH3Cl (chloromethane)
• C. Br2 (bromine)
• D. CCl4 (carbon tetrachloride)

Answer: (B)

Verified step by step guidance

1. Identify the molecular structure and polarity of each compound. Dipole-dipole forces occur between polar molecules, which have a permanent dipole moment due to differences in electronegativity and molecular geometry.
2. Analyze CH4 (methane): It is a tetrahedral molecule with four identical C-H bonds, which are nonpolar. The molecule is overall nonpolar, so it does not exhibit dipole-dipole forces.
3. Analyze CH3Cl (chloromethane): It has a tetrahedral shape but one hydrogen is replaced by chlorine, which is more electronegative. This creates a permanent dipole moment, making the molecule polar and capable of dipole-dipole interactions.
4. Analyze Br2 (bromine): It is a diatomic molecule consisting of two identical bromine atoms, making it nonpolar. Therefore, it does not have dipole-dipole forces, only London dispersion forces.
5. Analyze CCl4 (carbon tetrachloride): It has four identical C-Cl bonds arranged symmetrically in a tetrahedral shape, which cancels out the dipoles, making the molecule nonpolar. Hence, it does not exhibit dipole-dipole forces.