Given below are two statements — Assertion A and Reason R: Assertion A: Lithium halides are somewhat covalent in…
Chemical Bonding · Class 11 · JEE Main Previous Year Question
Given below are two statements — Assertion A and Reason R:
Assertion A: Lithium halides are somewhat covalent in nature.
Reason R: Lithium possesses high polarisation capability.
Choose the most appropriate answer:
- a
A is true but R is false
- b
A is false but R is true
- c
Both A and R are true but R is NOT the correct explanation of A
- d✓
Both A and R are true and R is the correct explanation of A
Both A and R are true and R is the correct explanation of A
🧠 Lithium () is the smallest alkali metal cation — its high charge density (charge/radius ratio) makes it an unusually polarizing cation for an alkali metal.
🗺️ Evaluate Assertion A:
Lithium halides (LiF, LiCl, LiBr, LiI) are classified as ionic but show measurable covalent character — for example, LiI is significantly covalent and soluble in organic solvents.
A is TRUE ✓
Evaluate Reason R:
has the smallest ionic radius among alkali metals (76 pm) and charge +1. Polarizing power = charge/radius. Despite low charge, the tiny radius gives the highest polarizing power among alkali metal ions → distorts anion electron cloud → introduces covalent character (Fajans' rules).
R is TRUE ✓ and R correctly explains A ✓
⚡ LiI is the most covalent Li halide (I⁻ is most polarizable). Even LiF shows more covalent character than NaF or KF due to small .
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