For each of the following substances, identify the intermolecular force or forces that predominate. Using your knowledge of the relative strength of the vaious forces, rank the substance in order of their normal boiling points. `Al_(2)O_(3), F_(2), H_(2)O, Br_(2), IC l, NaCl`

Options

A. `F_(2) lt Br_(2) lt IC l`
B. `H_(2)O lt NaCl lt Al_(2)O_(3)`
C. `ICl lt H_(2)O`
D. `H_(2)O lt ICl`

Explanation

To determine the predominant intermolecular forces in each of the given substances and rank them according to their normal boiling points, we can follow these steps:

### Step 1: Identify the Intermolecular Forces
1. **Al₂O₃ (Aluminum Oxide)**: This is an ionic compound. The predominant intermolecular force is ionic bonding.

2. **F₂ (Fluorine)**: This is a diatomic molecule consisting of the same atom. The predominant intermolecular force is Van der Waals forces (London dispersion forces).

3. **H₂O (Water)**: Water is a polar molecule and exhibits hydrogen bonding as its predominant intermolecular force.

4. **Br₂ (Bromine)**: Similar to F₂, Br₂ is a diatomic molecule of the same element. The predominant intermolecular force is also Van der Waals forces.

5. **ICl (Iodine Monochloride)**: This molecule is polar and exhibits dipole-dipole interactions as its predominant intermolecular force.

6. **NaCl (Sodium Chloride)**: Like Al₂O₃, NaCl is also an ionic compound with ionic bonding as the predominant force.

### Step 2: Rank the Substances by Boiling Points
Now that we have identified the predominant intermolecular forces, we can rank the substances based on the strength of these forces, which correlates with boiling points:

1. **Ionic Compounds**: These have the strongest intermolecular forces due to the strong attraction between oppositely charged ions.
- **1st**: Al₂O₃ (ionic bonding)
- **2nd**: NaCl (ionic bonding)

2. **Hydrogen Bonding**: This is the next strongest type of intermolecular force.
- **3rd**: H₂O (hydrogen bonding)

3. **Dipole-Dipole Interactions**: These are weaker than hydrogen bonds but stronger than Van der Waals forces.
- **4th**: ICl (dipole-dipole interactions)

4. **Van der Waals Forces**: These are the weakest intermolecular forces and are present in nonpolar molecules.
- **5th**: Br₂ (Van der Waals forces)
- **6th**: F₂ (Van der Waals forces)

### Final Ranking of Substances by Boiling Points
Based on the analysis above, the substances can be ranked in order of their normal boiling points as follows:
1. Al₂O₃
2. NaCl
3. H₂O
4. ICl
5. Br₂
6. F₂