Question

Strength hydrogen bonding is shown by

• A. water
• B. ammonia
• C. HF
• D. hydrogen sulphide

Answer 1

The Correct Option is C

To determine which substance exhibits strong hydrogen bonding, we need to consider the nature of hydrogen bonds and the properties of the substances in question.

Understanding Hydrogen Bonding: Hydrogen bonding is a type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom. It occurs when hydrogen is bonded to a highly electronegative atom such as nitrogen, oxygen, or fluorine. The hydrogen atom carries a partial positive charge and is attracted to the lone pair of electrons on a nearby electronegative atom.

Options Analysis:

• Water (H₂O): Water molecules form hydrogen bonds, but their strength is not the highest when compared to HF. The hydrogen bond it forms is due to the high electronegativity of oxygen.
• Ammonia (NH₃): Ammonia exhibits hydrogen bonding due to the nitrogen atom, but nitrogen's electronegativity is less than that of fluorine, leading to weaker hydrogen bonds compared to HF.
• Hydrogen fluoride (HF): HF exhibits the strongest hydrogen bonding among the options. Fluorine is the most electronegative element, and the HF bond creates a very strong hydrogen bond due to the large difference in electronegativity between hydrogen and fluorine.
• Hydrogen sulphide (H₂S): Hydrogen sulfide does not show significant hydrogen bonding because sulfur is significantly less electronegative compared to nitrogen, oxygen, and fluorine.

Conclusion: Among the given options, HF (hydrogen fluoride) shows the strongest hydrogen bonding because of the high electronegativity of fluorine, which strongly polarizes the bond with hydrogen, resulting in a significant dipole. This makes HF the correct answer for the strongest hydrogen bonding among the options.