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

• A. O2
• B. CH3Cl
• C. CCl4
• D. N2

Answer: (B)

Verified step by step guidance

1. Step 1: Understand what dipole–dipole interactions are. These are intermolecular forces that occur between molecules that have permanent dipoles, meaning the molecules are polar with a separation of positive and negative charges.
2. Step 2: Analyze the molecular structure and polarity of each substance given: O2, CH3Cl, CCl4, and N2. Determine if the molecule has a net dipole moment (is polar) or if it is nonpolar.
3. Step 3: For O2 and N2, recognize that these are diatomic molecules consisting of two identical atoms, so the electron distribution is equal, making them nonpolar with no permanent dipole moment.
4. Step 4: For CCl4, note that although the C–Cl bonds are polar, the molecule is tetrahedral and symmetrical, causing the dipoles to cancel out, resulting in a nonpolar molecule overall.
5. Step 5: For CH3Cl, observe that the molecule is asymmetrical with a polar C–Cl bond and the presence of hydrogen atoms, which creates a net dipole moment, making CH3Cl a polar molecule that exhibits dipole–dipole interactions.