Rank the following compounds in order of increasing strength of intermolecular forces: CH4, NH3, H2O, CO2.

• A. CO2 < CH4 < H2O < NH3
• B. H2O < NH3 < CO2 < CH4
• C. NH3 < CH4 < CO2 < H2O
• D. CH4 < CO2 < NH3 < H2O

Answer: (D)

Verified step by step guidance

1. Identify the types of intermolecular forces present in each compound: CH4, NH3, H2O, and CO2. Consider London dispersion forces, dipole-dipole interactions, and hydrogen bonding.
2. Recognize that CH4 and CO2 are nonpolar molecules, so their intermolecular forces are primarily London dispersion forces, which are generally weaker.
3. Note that NH3 and H2O are polar molecules capable of hydrogen bonding, which is a stronger type of intermolecular force compared to dipole-dipole and London forces.
4. Compare the strength of hydrogen bonding in NH3 and H2O. Water (H2O) has stronger hydrogen bonds due to its two hydrogen atoms bonded to highly electronegative oxygen, leading to stronger intermolecular attractions than NH3.
5. Rank the compounds from weakest to strongest intermolecular forces based on the above analysis: start with the nonpolar molecules (CH4, CO2), then NH3 with hydrogen bonding, and finally H2O with the strongest hydrogen bonding.