Correct order of boiling points of the given liquids is:
Correct answer: C. H2O > HF > NH3 > HCl
- A. H2O > HF > HCl > NH3
- B. HF > H2O > HCl > NH3
- C. H2O > HF > NH3 > HCl
- D. HF > H2O > NH3 > HCl
Explanation
H2O has a greater boiling point than HF because H2O can form 4 hydrogen bonds while HF has 2 hydrogen bonds and to break all the hydrogen bonds more energy is needed by H2O than HF. Due to the strong force of intermolecular hydrogen bonding. Due to the high difference in the electronegativity of hydrogen and fluorine as compared to that of hydrogen and nitrogen, more amount of energy is required to break the hydrogen-fluorine bond. Because of the high electronegativity of nitrogen than chlorine, the bond between N−H is stronger than a bond between H−Cl. Therefore the boiling point of NH3 is more than HCl.
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About Hydrogen Bonding
Hydrogen bonding is the strong attraction between hydrogen attached to nitrogen, oxygen or fluorine and an electronegative atom in the same or another molecule. It explains unusual boiling points, viscosity, surface tension, water's properties and the difference between intermolecular and intramolecular hydrogen bonding.
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