Match List I with List II
Choose the correct answer from the options given below:
| LIST I | LIST II |
|---|---|
| Coordination entity | Wavelength of light absorbed in nm |
| A. | I. 310 |
| B. | II. 475 |
| C. | III. 535 |
| D. | IV. 600 |
Choose the correct answer from the options given below:
- A.A-II, B-III, C-IV, D-I
- B.A-IV, B-I, C-III, D-II
- C.A-III, B-I, C-II, D-IV
- D.A-III, B-II, C-I, D-IV
Show answer and solution
Correct option: D
Solution
The spectrochemical series gives field strength order: CN⁻ > NH₃ > Cl⁻, and Cu²⁺ (d⁹) complexes absorb at much longer wavelengths (lower energy) than Co³⁺ (d⁶) complexes.
For the Co³⁺ complexes, stronger field ligands produce larger Δo, meaning higher energy (shorter wavelength) light is absorbed:
- [Co(CN)₆]³⁻: strongest field → highest Δo → absorbs at 310 nm (UV, C-I)
- [Co(NH₃)₆]³⁺: intermediate field → absorbs at 475 nm (B-II)
- [CoCl(NH₃)₅]²⁺: Cl⁻ weakens the field slightly vs pure NH₃ → absorbs at 535 nm (A-III)
- [Cu(H₂O)₄]²⁺: d⁹ Cu²⁺ with weak field water ligands → smallest Δo → absorbs at 600 nm (D-IV)
This gives A-III, B-II, C-I, D-IV, which is option 4.
For the Co³⁺ complexes, stronger field ligands produce larger Δo, meaning higher energy (shorter wavelength) light is absorbed:
- [Co(CN)₆]³⁻: strongest field → highest Δo → absorbs at 310 nm (UV, C-I)
- [Co(NH₃)₆]³⁺: intermediate field → absorbs at 475 nm (B-II)
- [CoCl(NH₃)₅]²⁺: Cl⁻ weakens the field slightly vs pure NH₃ → absorbs at 535 nm (A-III)
- [Cu(H₂O)₄]²⁺: d⁹ Cu²⁺ with weak field water ligands → smallest Δo → absorbs at 600 nm (D-IV)
This gives A-III, B-II, C-I, D-IV, which is option 4.
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