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Given below are two statements:
Statement I: Both $[Co(NH_3)_6]^{3+}$ and $[CoF_6]^{3-}$ complexes are octahedral but differ in their magnetic behaviour. Statement II: $[Co(NH_3)_6]^{3+}$ is diamagnetic whereas $[CoF_6]^{3-}$ is paramagnetic. In the light of the above statements,
choose the correct answer from the options given below:
Statement I: Both $[Co(NH_3)_6]^{3+}$ and $[CoF_6]^{3-}$ complexes are octahedral but differ in their magnetic behaviour. Statement II: $[Co(NH_3)_6]^{3+}$ is diamagnetic whereas $[CoF_6]^{3-}$ is paramagnetic. In the light of the above statements,
choose the correct answer from the options given below:
A
Statement I is true but Statement II is false.
B
Statement I is false but Statement II is true.
C
Both Statement I and Statement II are true.
D
Both Statement I and Statement II are false.
Detailed Solution
$[Co(NH_3)_6]^{3+}$ and $[CoF_6]^{3-}$ are both octahedral.
In $[Co(NH_3)_6]^{3+}$ ($NH_3$ is a strong field ligand), all electrons are paired ($t_{2g}^6e_g^0$), so it is diamagnetic.
In $[CoF_6]^{3-}$ ($F^-$ is a weak field ligand), there are four unpaired electrons ($t_{2g}^4e_g^2$), so it is paramagnetic.
So they differ in magnetic behaviour: both Statement I and Statement II are true.