Question

Hydrogen bond is strongest in

• A. $S - H --- O$
• B. $O - H --- S$
• C. $F - H --- F$
• D. $O - H --- N$

Answer 1

The Correct Option is C

The question asks which hydrogen bond is the strongest among the given options. Understanding the nature of hydrogen bonds is crucial in answering this question. Hydrogen bonds occur when hydrogen is covalently bonded to a highly electronegative atom, such as fluorine (F), oxygen (O), or nitrogen (N). The strength of the hydrogen bond is generally determined by the electronegativity of the atoms involved and the linearity of the bond.

Let's analyze each option:

• S - H --- O: Sulfur is less electronegative than oxygen and nitrogen, leading to a weaker hydrogen bond when compared to options involving these elements.
• O - H --- S: Although oxygen is highly electronegative, sulfur does not provide the conditions for a strong hydrogen bond as described above.
• F - H --- F: Fluorine is the most electronegative element, and this setup involves fluorine on both sides of the hydrogen bond, which creates a very strong hydrogen bond due to high electronegativity and linearity.
• O - H --- N: This is a strong hydrogen bond because both oxygen and nitrogen are electronegative, but it is not as strong as the F-H---F bond because fluorine is more electronegative than both oxygen and nitrogen.

Among the options, the hydrogen bond F - H --- F is the strongest because it involves the extremely electronegative fluorine atoms, enhancing both the bond strength and stability.

Therefore, the correct answer is F - H --- F.