Given below are two statements — Assertion A and Reason R: Assertion A: Dipole–dipole interactions are the only…
Chemical Bonding · Class 11 · JEE Main Previous Year Question
Given below are two statements — Assertion A and Reason R:
Assertion A: Dipole–dipole interactions are the only non-covalent interactions resulting in hydrogen bond formation.
Reason R: Fluorine is the most electronegative element and hydrogen bonds in HF are symmetrical.
Choose the most appropriate answer:
- a✓
A is false but R is true
- b
Both A and R are true but R is NOT the correct explanation of A
- c
A is true but R is false
- d
Both A and R are true and R is the correct explanation of A
A is false but R is true
🧠 Evaluate whether H-bonds are purely dipole–dipole in nature, and whether fluorine being most electronegative is the reason for H-bond formation.
🗺️ Evaluate Assertion A:
Hydrogen bonds have three components:
- Electrostatic/dipole–dipole interaction (dominant)
- Covalent character (partial orbital overlap between H and acceptor lone pair)
- Dispersion contribution
Saying "dipole–dipole interactions are the only non-covalent interactions" is FALSE — there is also a covalent/quantum mechanical component. The statement is an oversimplification.
A is FALSE ✗
Evaluate Reason R:
"Fluorine is the most electronegative element" → TRUE ✓
This is why F–H···F bonds are the strongest H-bonds. Fluorine's high electronegativity polarizes the H–F bond strongly, creating a highly positive H that strongly attracts lone pairs.
R is TRUE ✓
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