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

Question

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

1. A. [Co(NH3)3Cl3] (Correct answer)
2. B. [Co(NH3)4Cl2]
3. C. [Co(NH3)6]Cl3
4. D. [Co(NH3)5Cl]Cl

Correct Answer

Option A — [Co(NH3)3Cl3] (NTA awarded marks for both option 1 and option 2)

Detailed Solution & Explanation

The correct answer is [Co(NH$_3$)$_3$Cl$_3$] — NTA accepted both options 1 and 2 as correct.

Key Points

• Conductance depends on the number of ions furnished in solution; more ions $\Rightarrow$ higher conductance.
• [Co(NH$_3$)$_3$Cl$_3$] (Co$^{3+}$, all 3 Cl inside) is a neutral non-electrolyte $\Rightarrow$ 0 ions, minimum conductance.
• [Co(NH$_3$)$_4$Cl$_2$] (Co$^{2+}$, both Cl inside) is likewise a neutral non-electrolyte $\Rightarrow$ 0 ions, so it too has minimum conductance — hence both 1 and 2 are accepted.
• [Co(NH$_3$)$_6$]Cl$_3$ gives 4 ions and [Co(NH$_3$)$_5$Cl]Cl gives 2 ions — higher conductance.