Q39 · CSIR NET Chemistry, December 2019
Paper: CSIR NET December 2019 · Subject: Physical Chemistry · Chapter: Electrochemistry · Topic: Debye Huckel · Marks: 2 · Difficulty: Easy
The electrolyte solution that has the smallest Debye-length at 298 K is
(a)0.01 M NaCl
(b)$0.01 \mathrm{M} \mathrm{Na}_{2} \mathrm{SO}_{4}$
(c)$0.01 \mathrm{M} \mathrm{CuCl}_{2}$
(d)$0.01\,\mathrm{M}\,\mathrm{LaCl_3}$
Answer
Answer: D ✓ checked by 4AB · confidence high
Explanation
Debye length ∝ 1/√I. Ionic strengths at 0.01 M: NaCl 0.01, Na₂SO₄ 0.03, CuCl₂ 0.03, LaCl₃ ½(0.01×9 + 0.03×1) = 0.06. Highest I → shortest Debye length: LaCl₃.
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