Which of the following substances exhibits dipole–dipole (polar) intermolecular forces between its molecules?

• A. CCl4
• B. CH3Cl
• C. O2
• D. N2

Answer: (B)

Verified step by step guidance

1. Step 1: Understand that dipole–dipole intermolecular forces occur between molecules that have a permanent dipole moment, meaning the molecule is polar.
2. Step 2: Analyze the molecular geometry and electronegativity differences in each substance to determine if the molecule is polar or nonpolar.
3. Step 3: For CCl\_4, note that although C–Cl bonds are polar, the molecule is tetrahedral and symmetrical, so the dipoles cancel out, making it nonpolar.
4. Step 4: For CH\_3Cl, recognize that the molecule has a tetrahedral shape but the presence of the more electronegative Cl atom creates an uneven distribution of charge, resulting in a polar molecule with a permanent dipole moment.
5. Step 5: For O\_2 and N\_2, both are diatomic molecules consisting of identical atoms, so the bonds are nonpolar and the molecules have no permanent dipole moment, meaning they do not exhibit dipole–dipole forces.