The Hbr has highest boiling point followed by Kr , and
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The Hbr has highest boiling point due to presence of intermolecular H-bonding that is hydrogen bonding.
The electronegativity of bromine is greater than hydrogen atom. The electronegativity difference hydrogen atom and bromine atom is high. So, due to this a positive dipole is generated at hydrogen atom and partial negative charge, these partial charge is called dipole. In a HBr molecule one H-atom attracted by Br-atom of another atom by force of attraction and this partial force of attraction is called H-bonding.
Other all given molecules are arrange according to its molecular mass because boiling points is directly proportional to the molecular mass of molecule.
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