HBr's boiling point is lower than KBr's boiling point because KBr is an ionic compound with stronger intermolecular forces.
The question asks how the boiling point of HBr compares to KBr.
HBr's boiling point is lower than KBr's boiling point.
This is because KBr is an ionic compound, while HBr is a covalent compound. Ionic compounds have stronger intermolecular forces (ionic bonds) than covalent compounds (dipole-dipole interactions). Stronger intermolecular forces require more energy to overcome, so ionic compounds have higher boiling points than covalent compounds.
The electronegativity values of the elements in the compounds can also help to explain the difference in boiling points. Electronegativity is a measure of an atom's ability to attract electrons in a chemical bond. Potassium (K) is less electronegative than bromine (Br), so the K-Br bond is a polar covalent bond. Hydrogen (H) is more electronegative than bromine (Br), so the H-Br bond is a very polar covalent bond. The greater polarity of the H-Br bond results in stronger intermolecular forces (dipole-dipole interactions), which explains why HBr has a higher boiling point than KBr.
Conclusion: HBr's boiling point is lower than KBr's boiling point because KBr is an ionic compound with stronger intermolecular forces.