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Chemistry · Coordination Compounds

NEET (UG) 2025 — Question 58

Out of the following complex compounds, which of the compound will be having the minimum conductance in solution?

  1. Option A:

    [Co(NH3)3Cl3]\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{3} \mathrm{Cl}_{3}\right]

    Correct
  2. Option B:

    [Co(NHX3)X4ClX2]Cl\ce{[Co(NH3)4Cl2]Cl}

  3. Option C:

    [Co(NH3)6]Cl3\left[\mathrm{Co}\left(\mathrm{NH}_{3}\right)_{6}\right] \mathrm{Cl}_{3}

  4. Option D:

    [Co(NHX3)X5Cl]ClX2\ce{[Co(NH3)5Cl]Cl2}

Answer: A

Step-by-step solution

For coordination compounds, conductance depends on the number of ions produced. [Co(NHX3)X3ClX3]\ce{[Co(NH3)3Cl3]} is neutral (no free ions). [Co(NHX3)X4ClX2]Cl\ce{[Co(NH3)4Cl2]Cl} gives 2 ions: [Co(NHX3)X4ClX2]X+\ce{[Co(NH3)4Cl2]^+} and ClX−\ce{Cl^-}. [Co(NHX3)X5Cl]ClX2\ce{[Co(NH3)5Cl]Cl2} gives 3 ions: [Co(NHX3)X5Cl]X2+\ce{[Co(NH3)5Cl]^2+} and 2 ClX−\ce{2 Cl^-}. [Co(NHX3)X6]ClX3\ce{[Co(NH3)6]Cl3} gives 4 ions: [Co(NHX3)X6]X3+\ce{[Co(NH3)6]^3+} and 3 ClX−\ce{3 Cl^-}. Thus, the neutral complex has minimum conductance. Assuming Co(III) and correct formulas (B and D include counterions), the correct order is A < B < D < C, so answer is A.

Answer key and solution verified before publishing.

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Exam
NEET (UG) 2025
Paper
2025 paper
Subject
Chemistry
Chapter
Coordination Compounds
Topic
Fundamentals of Co-ordination Compounds

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