alleryAmong NaCl, NaBr, NaI: order of melting points:
ANaI > NaBr > NaCl
BNaCl > NaBr > NaI (smaller anion = stronger lattice)
CAll equal
DNaBr > NaCl > NaI
Answer & Solution
Correct answer: B. NaCl > NaBr > NaI (smaller anion = stronger lattice)
As anion size grows (Cl⁻ < Br⁻ < I⁻), inter-ionic distance r grows, lattice energy ∝ 1/r decreases.
**Hence melting point decreases:** NaCl (801°C) > NaBr (747°C) > NaI (661°C).
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