Given below are two statements: Statement I: Among [mathrmCu(mathrmNH_3)_4]^2+$[\mathrm{Cu}(\mathrm{NH}_{3})_{4}]^{2+}$, [mathrmNi(mathrmen)_3]^2+$[\mathrm{Ni}(\mathrm{en})_{3}]^{2+}$, [mathrmNi(mathrmNH_3)_6]^2+$[\mathrm{Ni}(\mathrm{NH}_{3})_{6}]^{2+}$ and [mathrmMn(mathrmH_2mathrmO)_6]^2+$[\mathrm{Mn}(\mathrm{H}_{2}\mathrm{O})_{6}]^{2+}$, [mathrmMn(mathrmH_2mathrmO)_6]^2+$[\mathrm{Mn}(\mathrm{H}_{2}\mathrm{O})_{6}]^{2+}$ has the maximum number of unpaired electrons. Statement II: The number of pairs among \[NiCl_4]^2-, [Ni(CO)_4]\$\{[NiCl_{4}]^{2-}, [Ni(CO)_{4}]\}$, \[NiCl_4]^2-, [Ni(CN)_4]^2-\$\{[NiCl_{4}]^{2-}, [Ni(CN)_{4}]^{2-}\}$ and \[Ni(CO)_4], [Ni(CN)_4]^2-\$\{[Ni(CO)_{4}], [Ni(CN)_{4}]^{2-}\}$ that contain only diamagnetic species is two. In the light of the above statements, choose the correct answer from the options given below:

### Core Logic Evaluating Statement I: - [Cu(NH_3)_4]^2+$[Cu(NH_3)_4]^{2+}$: Cu^2+$Cu^{2+}$ is 3d^9$3d^9$, 1 unpaired electron. - [Ni(en)_3]^2+$[Ni(en)_3]^{2+}$: Ni^2+$Ni^{2+}$ is 3d^8$3d^8$, in octahedral field, 2 unpaired electrons. - [Ni(NH_3)_6]^2+$[Ni(NH_3)_6]^{2+}$: Ni^2+$Ni^{2+}$ is 3d^8$3d^8$, 2 unpaired electrons. - [Mn(H_2O)_6]^2+$[Mn(H_2O)_6]^{2+}$: Mn^2+$Mn^{2+}$ is 3d^5$3d^5$, weak field ligand H_2O$H_2O$ leads to high spin, 5 unpaired electrons. So [Mn(H_2O)_6]^2+$[Mn(H_2O)_6]^{2+}$ has the maximum number of unpaired electrons. Statement I is true. Evaluating Statement II: - [Ni(CO)_4]$[Ni(CO)_4]$: Ni(0)$Ni(0)$ is 3d^8 4s^2$3d^8 4s^2$, strong field CO pairs electrons to 3d^10$3d^{10}$, diamagnetic (0 unpaired). - [Ni(CN)_4]^2-$[Ni(CN)_4]^{2-}$: Ni^2+$Ni^{2+}$ is 3d^8$3d^8$, strong field CN^-$CN^-$ forces pairing rightarrow dsp^2$\rightarrow dsp^2$ square planar, diamagnetic (0 unpaired). - [NiCl_4]^2-$[NiCl_4]^{2-}$: Ni^2+$Ni^{2+}$ is 3d^8$3d^8$, weak field Cl^-$Cl^-$ does not pair rightarrow sp^3$\rightarrow sp^3$ tetrahedral, paramagnetic (2 unpaired). The pairs containing ONLY diamagnetic species: - \[NiCl_4]^2-, [Ni(CO)_4]\$\{[NiCl_4]^{2-}, [Ni(CO)_4]\}$ rightarrow$\rightarrow$ 1 para, 1 dia (No) - \[NiCl_4]^2-, [Ni(CN)_4]^2-\$\{[NiCl_4]^{2-}, [Ni(CN)_4]^{2-}\}$ rightarrow$\rightarrow$ 1 para, 1 dia (No) - \[Ni(CO)_4], [Ni(CN)_4]^2-\$\{[Ni(CO)_4], [Ni(CN)_4]^{2-}\}$ rightarrow$\rightarrow$ Both dia (Yes) The number of such pairs is exactly ONE. Statement II says two, so it is false. ### Step 1: Final Conclusion Statement I is true, Statement II is false. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Chemistry: Coordination Compounds