274268
Which of the following statements is not correct?
1 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in the state of hybridization of nickel
2 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in the magnetic properties
3 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in geometry
4 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ of differ in primary valencies
5 Nickel ion has the same secondary valency in the complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$
Explanation:
(D) : $\mathrm{In}\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ complex nickel is present in +2 oxidation state. $\mathrm{Cl}^{-}$is weak field ligand then pairing of metal d-electron is not possible $\left[\mathrm{NiCl}_{4}\right]^{2-}$ $\mathrm{Ni}^{2+}: \mathrm{d}^{8}$ Geometry of $\left[\mathrm{NiCl}_{4}\right]^{2-} \Rightarrow$ Tetrahedral Number of unpaired electron $=2$ Magnetic moment $=\sqrt{2(2+2)}=\sqrt{8}=2.84$ B.M. Primary valence is satisfied by oxidation state of metal. Here primary valency is +2 Secondary valency is satisfied by coordination numbers of complex. Here secondary valency is 6 . $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ $\mathrm{Ni}^{2+}: \mathrm{d}^{8}$ Geometry $\Rightarrow$ Square planar Magnetic moment $=$ oxidation state $=+2$ Secondary valency $=$ Coordination No. $=6$ Hence, the complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{NiCl}_{4}\right]^{2-}$ of same in primary valency of nickel.
Kerala-CEE-2007
COORDINATION COMPOUNDS
274276
The crystal field splitting energy (CFSE) for $\left[\mathrm{CoCl}_{6}\right]^{4-}$ is about $18000 \mathrm{~cm}^{-1}$. What would be the CFSE value for $\left[\mathrm{CoCl}_{4}\right]^{2-}$ ?
1 $1800 \mathrm{~cm}^{-1}$
2 $8000 \mathrm{~cm}^{-1}$
3 $16000 \mathrm{~cm}^{-1}$
4 $2000 \mathrm{~cm}^{-1}$
Explanation:
(B) : $\left[\mathrm{CoCl}_{6}\right]^{4-}$ is a octahedral complex. The CFSE of the compound is $18000 \mathrm{~cm}^{-1}$ i.e. $\Delta_{\mathrm{o}}=18000 \mathrm{~cm}^{-1}$ $\left[\mathrm{COCl}_{4}\right]^{2-}$ is a tetrahedral complex. Now, from relation between $\Delta_{\mathrm{oh}}$ and $\Delta_{\mathrm{t}}$ is - $\Delta_{\mathrm{t}} =\frac{4}{9} \Delta_{\mathrm{o}}$ $\Delta_{\mathrm{t}} =\frac{4}{9} \times 18000 \mathrm{~cm}^{-1}$ $\Delta_{\mathrm{t}} =8000 \mathrm{~cm}^{-1}$
Karnataka CET-17.06.2022
COORDINATION COMPOUNDS
274286
The crystal field stabilisation energy (CFSE) of $\left[\mathrm{CoF}_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3}\right]\left(\Delta_{0}<\mathrm{P}\right)$ is
1 $-0.8 \Delta_{0}$
2 $-0.8 \Delta_{0}+2 \mathrm{P}$
3 $-0.4 \Delta_{0}$
4 $-0.4 \Delta_{0}+P$
Explanation:
(C) : $\left[\mathrm{CoF}_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3}\right]$ Let, $\mathrm{X}$ be the oxidation state of $\mathrm{Co}$. \(\mathrm{x}+3(-1)+3(0)=0\) \(\mathrm{x}=+3\)\mathrm{CO}^{3+}=[\mathrm{Ar}] 3 \mathrm{~d}^6\) $\mathrm{CFSE}=\left[-0.4 \times \mathrm{N}_{\mathrm{t}_{2 \mathrm{~g}}}+0.6 \times \mathrm{N}_{\mathrm{e}_{\mathrm{g}}}\right] \Delta_{\mathrm{o}}$ CFSE $=[-0.4 \times 4+0.6 \times 2] \Delta_{\text {o }}$ $\mathrm{CFSE}=[-1.6+1.2] \Delta_{\mathrm{o}}$ CFSE $=-0.4 \Delta_{\text {o }}$
JEE Main 2020
COORDINATION COMPOUNDS
274280
The crystal field stabilization energy (CFSE) and magnetic moment (spin-only) of an octahedral aqua complex of a metal ion $\left(\mathrm{M}^{+}\right)$are $-0.8 \Delta_{0}$ and $3.87 \mathrm{BM}$, respectively. identify $\left(\mathrm{M}^{2+}\right)$.
1 $\mathrm{V}^{3+}$
2 $\mathrm{Cr}^{3+}$
3 $\mathrm{Mn}^{4+}$
4 $\mathrm{Co}^{2+}$
Explanation:
(D) : The metal ion is $\mathrm{Co}^{2+}$ because it form the aqua complex with +2 oxidation state. $\mathrm{Co}^{2+}=[\mathrm{Ar}] 3 \mathrm{~d}^{7}$ (Hight spin) Unpaired electron $(\mathrm{n})=3$ $\therefore \quad \mu_{\mathrm{s}}=\sqrt{\mathrm{n}(\mathrm{n}+2)}$ $\mu_{\mathrm{s}}=\sqrt{3(3+2)}$ $\mu_{\mathrm{s}}=3.87 \mathrm{BM}$ $\mathrm{CFSC}=\left[-0.4 \times \mathrm{Nt}_{2 \mathrm{~g}}+0.6 \times \mathrm{N}_{\mathrm{e}_{\mathrm{g}}}\right] \Delta_{\mathrm{o}}$ $\mathrm{CFSE}=[-0.4 \times 5+0.6 \times 2] \Delta_{\mathrm{o}}$ CFSE $=-0.8 \Delta_{\mathrm{o}}$
NEET Test Series from KOTA - 10 Papers In MS WORD
WhatsApp Here
COORDINATION COMPOUNDS
274268
Which of the following statements is not correct?
1 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in the state of hybridization of nickel
2 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in the magnetic properties
3 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in geometry
4 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ of differ in primary valencies
5 Nickel ion has the same secondary valency in the complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$
Explanation:
(D) : $\mathrm{In}\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ complex nickel is present in +2 oxidation state. $\mathrm{Cl}^{-}$is weak field ligand then pairing of metal d-electron is not possible $\left[\mathrm{NiCl}_{4}\right]^{2-}$ $\mathrm{Ni}^{2+}: \mathrm{d}^{8}$ Geometry of $\left[\mathrm{NiCl}_{4}\right]^{2-} \Rightarrow$ Tetrahedral Number of unpaired electron $=2$ Magnetic moment $=\sqrt{2(2+2)}=\sqrt{8}=2.84$ B.M. Primary valence is satisfied by oxidation state of metal. Here primary valency is +2 Secondary valency is satisfied by coordination numbers of complex. Here secondary valency is 6 . $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ $\mathrm{Ni}^{2+}: \mathrm{d}^{8}$ Geometry $\Rightarrow$ Square planar Magnetic moment $=$ oxidation state $=+2$ Secondary valency $=$ Coordination No. $=6$ Hence, the complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{NiCl}_{4}\right]^{2-}$ of same in primary valency of nickel.
Kerala-CEE-2007
COORDINATION COMPOUNDS
274276
The crystal field splitting energy (CFSE) for $\left[\mathrm{CoCl}_{6}\right]^{4-}$ is about $18000 \mathrm{~cm}^{-1}$. What would be the CFSE value for $\left[\mathrm{CoCl}_{4}\right]^{2-}$ ?
1 $1800 \mathrm{~cm}^{-1}$
2 $8000 \mathrm{~cm}^{-1}$
3 $16000 \mathrm{~cm}^{-1}$
4 $2000 \mathrm{~cm}^{-1}$
Explanation:
(B) : $\left[\mathrm{CoCl}_{6}\right]^{4-}$ is a octahedral complex. The CFSE of the compound is $18000 \mathrm{~cm}^{-1}$ i.e. $\Delta_{\mathrm{o}}=18000 \mathrm{~cm}^{-1}$ $\left[\mathrm{COCl}_{4}\right]^{2-}$ is a tetrahedral complex. Now, from relation between $\Delta_{\mathrm{oh}}$ and $\Delta_{\mathrm{t}}$ is - $\Delta_{\mathrm{t}} =\frac{4}{9} \Delta_{\mathrm{o}}$ $\Delta_{\mathrm{t}} =\frac{4}{9} \times 18000 \mathrm{~cm}^{-1}$ $\Delta_{\mathrm{t}} =8000 \mathrm{~cm}^{-1}$
Karnataka CET-17.06.2022
COORDINATION COMPOUNDS
274286
The crystal field stabilisation energy (CFSE) of $\left[\mathrm{CoF}_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3}\right]\left(\Delta_{0}<\mathrm{P}\right)$ is
1 $-0.8 \Delta_{0}$
2 $-0.8 \Delta_{0}+2 \mathrm{P}$
3 $-0.4 \Delta_{0}$
4 $-0.4 \Delta_{0}+P$
Explanation:
(C) : $\left[\mathrm{CoF}_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3}\right]$ Let, $\mathrm{X}$ be the oxidation state of $\mathrm{Co}$. \(\mathrm{x}+3(-1)+3(0)=0\) \(\mathrm{x}=+3\)\mathrm{CO}^{3+}=[\mathrm{Ar}] 3 \mathrm{~d}^6\) $\mathrm{CFSE}=\left[-0.4 \times \mathrm{N}_{\mathrm{t}_{2 \mathrm{~g}}}+0.6 \times \mathrm{N}_{\mathrm{e}_{\mathrm{g}}}\right] \Delta_{\mathrm{o}}$ CFSE $=[-0.4 \times 4+0.6 \times 2] \Delta_{\text {o }}$ $\mathrm{CFSE}=[-1.6+1.2] \Delta_{\mathrm{o}}$ CFSE $=-0.4 \Delta_{\text {o }}$
JEE Main 2020
COORDINATION COMPOUNDS
274280
The crystal field stabilization energy (CFSE) and magnetic moment (spin-only) of an octahedral aqua complex of a metal ion $\left(\mathrm{M}^{+}\right)$are $-0.8 \Delta_{0}$ and $3.87 \mathrm{BM}$, respectively. identify $\left(\mathrm{M}^{2+}\right)$.
1 $\mathrm{V}^{3+}$
2 $\mathrm{Cr}^{3+}$
3 $\mathrm{Mn}^{4+}$
4 $\mathrm{Co}^{2+}$
Explanation:
(D) : The metal ion is $\mathrm{Co}^{2+}$ because it form the aqua complex with +2 oxidation state. $\mathrm{Co}^{2+}=[\mathrm{Ar}] 3 \mathrm{~d}^{7}$ (Hight spin) Unpaired electron $(\mathrm{n})=3$ $\therefore \quad \mu_{\mathrm{s}}=\sqrt{\mathrm{n}(\mathrm{n}+2)}$ $\mu_{\mathrm{s}}=\sqrt{3(3+2)}$ $\mu_{\mathrm{s}}=3.87 \mathrm{BM}$ $\mathrm{CFSC}=\left[-0.4 \times \mathrm{Nt}_{2 \mathrm{~g}}+0.6 \times \mathrm{N}_{\mathrm{e}_{\mathrm{g}}}\right] \Delta_{\mathrm{o}}$ $\mathrm{CFSE}=[-0.4 \times 5+0.6 \times 2] \Delta_{\mathrm{o}}$ CFSE $=-0.8 \Delta_{\mathrm{o}}$
274268
Which of the following statements is not correct?
1 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in the state of hybridization of nickel
2 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in the magnetic properties
3 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in geometry
4 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ of differ in primary valencies
5 Nickel ion has the same secondary valency in the complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$
Explanation:
(D) : $\mathrm{In}\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ complex nickel is present in +2 oxidation state. $\mathrm{Cl}^{-}$is weak field ligand then pairing of metal d-electron is not possible $\left[\mathrm{NiCl}_{4}\right]^{2-}$ $\mathrm{Ni}^{2+}: \mathrm{d}^{8}$ Geometry of $\left[\mathrm{NiCl}_{4}\right]^{2-} \Rightarrow$ Tetrahedral Number of unpaired electron $=2$ Magnetic moment $=\sqrt{2(2+2)}=\sqrt{8}=2.84$ B.M. Primary valence is satisfied by oxidation state of metal. Here primary valency is +2 Secondary valency is satisfied by coordination numbers of complex. Here secondary valency is 6 . $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ $\mathrm{Ni}^{2+}: \mathrm{d}^{8}$ Geometry $\Rightarrow$ Square planar Magnetic moment $=$ oxidation state $=+2$ Secondary valency $=$ Coordination No. $=6$ Hence, the complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{NiCl}_{4}\right]^{2-}$ of same in primary valency of nickel.
Kerala-CEE-2007
COORDINATION COMPOUNDS
274276
The crystal field splitting energy (CFSE) for $\left[\mathrm{CoCl}_{6}\right]^{4-}$ is about $18000 \mathrm{~cm}^{-1}$. What would be the CFSE value for $\left[\mathrm{CoCl}_{4}\right]^{2-}$ ?
1 $1800 \mathrm{~cm}^{-1}$
2 $8000 \mathrm{~cm}^{-1}$
3 $16000 \mathrm{~cm}^{-1}$
4 $2000 \mathrm{~cm}^{-1}$
Explanation:
(B) : $\left[\mathrm{CoCl}_{6}\right]^{4-}$ is a octahedral complex. The CFSE of the compound is $18000 \mathrm{~cm}^{-1}$ i.e. $\Delta_{\mathrm{o}}=18000 \mathrm{~cm}^{-1}$ $\left[\mathrm{COCl}_{4}\right]^{2-}$ is a tetrahedral complex. Now, from relation between $\Delta_{\mathrm{oh}}$ and $\Delta_{\mathrm{t}}$ is - $\Delta_{\mathrm{t}} =\frac{4}{9} \Delta_{\mathrm{o}}$ $\Delta_{\mathrm{t}} =\frac{4}{9} \times 18000 \mathrm{~cm}^{-1}$ $\Delta_{\mathrm{t}} =8000 \mathrm{~cm}^{-1}$
Karnataka CET-17.06.2022
COORDINATION COMPOUNDS
274286
The crystal field stabilisation energy (CFSE) of $\left[\mathrm{CoF}_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3}\right]\left(\Delta_{0}<\mathrm{P}\right)$ is
1 $-0.8 \Delta_{0}$
2 $-0.8 \Delta_{0}+2 \mathrm{P}$
3 $-0.4 \Delta_{0}$
4 $-0.4 \Delta_{0}+P$
Explanation:
(C) : $\left[\mathrm{CoF}_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3}\right]$ Let, $\mathrm{X}$ be the oxidation state of $\mathrm{Co}$. \(\mathrm{x}+3(-1)+3(0)=0\) \(\mathrm{x}=+3\)\mathrm{CO}^{3+}=[\mathrm{Ar}] 3 \mathrm{~d}^6\) $\mathrm{CFSE}=\left[-0.4 \times \mathrm{N}_{\mathrm{t}_{2 \mathrm{~g}}}+0.6 \times \mathrm{N}_{\mathrm{e}_{\mathrm{g}}}\right] \Delta_{\mathrm{o}}$ CFSE $=[-0.4 \times 4+0.6 \times 2] \Delta_{\text {o }}$ $\mathrm{CFSE}=[-1.6+1.2] \Delta_{\mathrm{o}}$ CFSE $=-0.4 \Delta_{\text {o }}$
JEE Main 2020
COORDINATION COMPOUNDS
274280
The crystal field stabilization energy (CFSE) and magnetic moment (spin-only) of an octahedral aqua complex of a metal ion $\left(\mathrm{M}^{+}\right)$are $-0.8 \Delta_{0}$ and $3.87 \mathrm{BM}$, respectively. identify $\left(\mathrm{M}^{2+}\right)$.
1 $\mathrm{V}^{3+}$
2 $\mathrm{Cr}^{3+}$
3 $\mathrm{Mn}^{4+}$
4 $\mathrm{Co}^{2+}$
Explanation:
(D) : The metal ion is $\mathrm{Co}^{2+}$ because it form the aqua complex with +2 oxidation state. $\mathrm{Co}^{2+}=[\mathrm{Ar}] 3 \mathrm{~d}^{7}$ (Hight spin) Unpaired electron $(\mathrm{n})=3$ $\therefore \quad \mu_{\mathrm{s}}=\sqrt{\mathrm{n}(\mathrm{n}+2)}$ $\mu_{\mathrm{s}}=\sqrt{3(3+2)}$ $\mu_{\mathrm{s}}=3.87 \mathrm{BM}$ $\mathrm{CFSC}=\left[-0.4 \times \mathrm{Nt}_{2 \mathrm{~g}}+0.6 \times \mathrm{N}_{\mathrm{e}_{\mathrm{g}}}\right] \Delta_{\mathrm{o}}$ $\mathrm{CFSE}=[-0.4 \times 5+0.6 \times 2] \Delta_{\mathrm{o}}$ CFSE $=-0.8 \Delta_{\mathrm{o}}$
274268
Which of the following statements is not correct?
1 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in the state of hybridization of nickel
2 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in the magnetic properties
3 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ differ in geometry
4 The complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ of differ in primary valencies
5 Nickel ion has the same secondary valency in the complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$
Explanation:
(D) : $\mathrm{In}\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ complex nickel is present in +2 oxidation state. $\mathrm{Cl}^{-}$is weak field ligand then pairing of metal d-electron is not possible $\left[\mathrm{NiCl}_{4}\right]^{2-}$ $\mathrm{Ni}^{2+}: \mathrm{d}^{8}$ Geometry of $\left[\mathrm{NiCl}_{4}\right]^{2-} \Rightarrow$ Tetrahedral Number of unpaired electron $=2$ Magnetic moment $=\sqrt{2(2+2)}=\sqrt{8}=2.84$ B.M. Primary valence is satisfied by oxidation state of metal. Here primary valency is +2 Secondary valency is satisfied by coordination numbers of complex. Here secondary valency is 6 . $\left[\mathrm{Ni}(\mathrm{CN})_{4}\right]^{2-}$ $\mathrm{Ni}^{2+}: \mathrm{d}^{8}$ Geometry $\Rightarrow$ Square planar Magnetic moment $=$ oxidation state $=+2$ Secondary valency $=$ Coordination No. $=6$ Hence, the complexes $\left[\mathrm{NiCl}_{4}\right]^{2-}$ and $\left[\mathrm{NiCl}_{4}\right]^{2-}$ of same in primary valency of nickel.
Kerala-CEE-2007
COORDINATION COMPOUNDS
274276
The crystal field splitting energy (CFSE) for $\left[\mathrm{CoCl}_{6}\right]^{4-}$ is about $18000 \mathrm{~cm}^{-1}$. What would be the CFSE value for $\left[\mathrm{CoCl}_{4}\right]^{2-}$ ?
1 $1800 \mathrm{~cm}^{-1}$
2 $8000 \mathrm{~cm}^{-1}$
3 $16000 \mathrm{~cm}^{-1}$
4 $2000 \mathrm{~cm}^{-1}$
Explanation:
(B) : $\left[\mathrm{CoCl}_{6}\right]^{4-}$ is a octahedral complex. The CFSE of the compound is $18000 \mathrm{~cm}^{-1}$ i.e. $\Delta_{\mathrm{o}}=18000 \mathrm{~cm}^{-1}$ $\left[\mathrm{COCl}_{4}\right]^{2-}$ is a tetrahedral complex. Now, from relation between $\Delta_{\mathrm{oh}}$ and $\Delta_{\mathrm{t}}$ is - $\Delta_{\mathrm{t}} =\frac{4}{9} \Delta_{\mathrm{o}}$ $\Delta_{\mathrm{t}} =\frac{4}{9} \times 18000 \mathrm{~cm}^{-1}$ $\Delta_{\mathrm{t}} =8000 \mathrm{~cm}^{-1}$
Karnataka CET-17.06.2022
COORDINATION COMPOUNDS
274286
The crystal field stabilisation energy (CFSE) of $\left[\mathrm{CoF}_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3}\right]\left(\Delta_{0}<\mathrm{P}\right)$ is
1 $-0.8 \Delta_{0}$
2 $-0.8 \Delta_{0}+2 \mathrm{P}$
3 $-0.4 \Delta_{0}$
4 $-0.4 \Delta_{0}+P$
Explanation:
(C) : $\left[\mathrm{CoF}_{3}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3}\right]$ Let, $\mathrm{X}$ be the oxidation state of $\mathrm{Co}$. \(\mathrm{x}+3(-1)+3(0)=0\) \(\mathrm{x}=+3\)\mathrm{CO}^{3+}=[\mathrm{Ar}] 3 \mathrm{~d}^6\) $\mathrm{CFSE}=\left[-0.4 \times \mathrm{N}_{\mathrm{t}_{2 \mathrm{~g}}}+0.6 \times \mathrm{N}_{\mathrm{e}_{\mathrm{g}}}\right] \Delta_{\mathrm{o}}$ CFSE $=[-0.4 \times 4+0.6 \times 2] \Delta_{\text {o }}$ $\mathrm{CFSE}=[-1.6+1.2] \Delta_{\mathrm{o}}$ CFSE $=-0.4 \Delta_{\text {o }}$
JEE Main 2020
COORDINATION COMPOUNDS
274280
The crystal field stabilization energy (CFSE) and magnetic moment (spin-only) of an octahedral aqua complex of a metal ion $\left(\mathrm{M}^{+}\right)$are $-0.8 \Delta_{0}$ and $3.87 \mathrm{BM}$, respectively. identify $\left(\mathrm{M}^{2+}\right)$.
1 $\mathrm{V}^{3+}$
2 $\mathrm{Cr}^{3+}$
3 $\mathrm{Mn}^{4+}$
4 $\mathrm{Co}^{2+}$
Explanation:
(D) : The metal ion is $\mathrm{Co}^{2+}$ because it form the aqua complex with +2 oxidation state. $\mathrm{Co}^{2+}=[\mathrm{Ar}] 3 \mathrm{~d}^{7}$ (Hight spin) Unpaired electron $(\mathrm{n})=3$ $\therefore \quad \mu_{\mathrm{s}}=\sqrt{\mathrm{n}(\mathrm{n}+2)}$ $\mu_{\mathrm{s}}=\sqrt{3(3+2)}$ $\mu_{\mathrm{s}}=3.87 \mathrm{BM}$ $\mathrm{CFSC}=\left[-0.4 \times \mathrm{Nt}_{2 \mathrm{~g}}+0.6 \times \mathrm{N}_{\mathrm{e}_{\mathrm{g}}}\right] \Delta_{\mathrm{o}}$ $\mathrm{CFSE}=[-0.4 \times 5+0.6 \times 2] \Delta_{\mathrm{o}}$ CFSE $=-0.8 \Delta_{\mathrm{o}}$
