!<Answer>!
To rank substances in decreasing order of the strength of intermolecular forces, we need to consider the types of intermolecular forces present in each substance.
1. Hydrogen bonding: This is the strongest type of intermolecular force. It occurs when hydrogen is bonded to a highly electronegative atom such as nitrogen, oxygen, or fluorine. Examples of substances that exhibit hydrogen bonding are water (H2O) and ammonia (NH3).
2. Dipole-dipole forces: These forces occur between the positive end of one polar molecule and the negative end of another polar molecule. They are weaker than hydrogen bonding. Examples of substances that exhibit dipole-dipole forces are hydrogen sulfide (H2S) and hydrogen chloride (HCl).
3. London dispersion forces: These forces exist between all molecules, regardless of their polarity. They occur due to temporary shifts in electron distribution, leading to temporary dipoles. London dispersion forces are the weakest intermolecular forces. Examples of substances that exhibit London dispersion forces are noble gases like helium (He) and nonpolar molecules like methane (CH4).
Based on this information, we can rank the substances in decreasing order of the strength of the intermolecular forces:
1. Substances with hydrogen bonding (e.g., water and ammonia)
2. Substances with dipole-dipole forces (e.g., hydrogen sulfide and hydrogen chloride)
3. Substances with London dispersion forces (e.g., helium and methane)
Therefore, the ranking of the substances from strongest to weakest intermolecular forces is:
1. Strongest: Substances with hydrogen bonding
2. Second Strongest: Substances with dipole-dipole forces
3. Third Strongest: Substances with London dispersion forces
4. Weakest: Substances with no significant intermolecular forces
~ Sun
