Final answer:
The boiling point of a compound depends on the strength of the intermolecular forces between its molecules. Potassium fluoride (KF) has the highest boiling point due to its ionic nature, while carbon tetrafluoride (CF4) has the lowest boiling point due to weak London dispersion forces.
Step-by-step explanation:
The boiling point of a compound depends on the strength of the intermolecular forces between its molecules. Generally, compounds with stronger intermolecular forces have higher boiling points. In this case, we need to compare potassium fluoride (KF), carbon tetrafluoride (CF4), and bromoform (CHBr3).
Potassium fluoride (KF) is an ionic compound, which means it has strong electrostatic forces of attraction between oppositely charged ions.
These ionic compounds generally have high boiling points due to the strong forces. Carbon tetrafluoride (CF4) is a covalent compound with only London dispersion forces between its molecules.
Bromoform (CHBr3) is also a covalent compound, but it has larger and more polar molecules than CF4, so it experiences stronger dipole-dipole interactions, which contribute to higher boiling points compared to CF4.
Therefore, the ranking in decreasing boiling points would be:
1. Potassium fluoride (KF)
2. Bromoform (CHBr3)
3. Carbon tetrafluoride (CF4)