Q103 / 240 · KCET 2026 · Chemistry
Match List-I with List-II
List-I (Complex) List-II (Geometry) (a) $[\text{Co(NH}_3\text{)}_6]^{3+}$ (i) Trigonal bipyramidal (b) $[\text{NiCl}_4]^{2-}$ (ii) Octahedral (c) $[\text{Ni(CN)}_4]^{2-}$ (iii) Tetrahedral (d) $[\text{Fe(CO)}_5]$ (iv) Square planar
Choose the correct answer from the options given below.
| List-I (Complex) | List-II (Geometry) | ||
|---|---|---|---|
| (a) | $[\text{Co(NH}_3\text{)}_6]^{3+}$ | (i) | Trigonal bipyramidal |
| (b) | $[\text{NiCl}_4]^{2-}$ | (ii) | Octahedral |
| (c) | $[\text{Ni(CN)}_4]^{2-}$ | (iii) | Tetrahedral |
| (d) | $[\text{Fe(CO)}_5]$ | (iv) | Square planar |
- Correct answerAa-ii, b-iii, c-iv, d-i
- Ba-ii, b-i, c-iii, d-iv
- Ca-iii, b-ii, c-iv, d-i
- Da-i, b-iii, c-iv, d-ii
Solution
For $[\text{Co(NH}_3\text{)}_6]^{3+}$, the coordination number is $6$, which corresponds to an octahedral geometry. Thus, (a) matches with (ii).
For $[\text{NiCl}_4]^{2-}$, $\text{Ni}$ is in the $+2$ oxidation state with a $3d^8$ configuration. Since $\text{Cl}^-$ is a weak field ligand, no pairing occurs, leading to $sp^3$ hybridization and a tetrahedral geometry. Thus, (b) matches with (iii).
For $[\text{Ni(CN)}_4]^{2-}$, $\text{Ni}$ is in the $+2$ oxidation state with a $3d^8$ configuration. Since $\text{CN}^-$ is a strong field ligand, pairing of electrons occurs, leading to $dsp^2$ hybridization and a square planar geometry. Thus, (c) matches with (iv).
For $[\text{Fe(CO)}_5]$, the coordination number is $5$. $\text{Fe}$ is in the $0$ oxidation state with a $3d^6 4s^2$ configuration. The strong field ligand $\text{CO}$ causes pairing of electrons, resulting in $dsp^3$ hybridization and a trigonal bipyramidal geometry. Thus, (d) matches with (i).
The correct matching is a-ii, b-iii, c-iv, d-i.
Answer: a-ii, b-iii, c-iv, d-i
For $[\text{NiCl}_4]^{2-}$, $\text{Ni}$ is in the $+2$ oxidation state with a $3d^8$ configuration. Since $\text{Cl}^-$ is a weak field ligand, no pairing occurs, leading to $sp^3$ hybridization and a tetrahedral geometry. Thus, (b) matches with (iii).
For $[\text{Ni(CN)}_4]^{2-}$, $\text{Ni}$ is in the $+2$ oxidation state with a $3d^8$ configuration. Since $\text{CN}^-$ is a strong field ligand, pairing of electrons occurs, leading to $dsp^2$ hybridization and a square planar geometry. Thus, (c) matches with (iv).
For $[\text{Fe(CO)}_5]$, the coordination number is $5$. $\text{Fe}$ is in the $0$ oxidation state with a $3d^6 4s^2$ configuration. The strong field ligand $\text{CO}$ causes pairing of electrons, resulting in $dsp^3$ hybridization and a trigonal bipyramidal geometry. Thus, (d) matches with (i).
The correct matching is a-ii, b-iii, c-iv, d-i.
Answer: a-ii, b-iii, c-iv, d-i
Hence, the correct answer is option: 'A'.