Assertion: `[CoF_(6)]^(3-)` is a paramagnetic.
Reason: `Co^(3+)" has 3d"^(6)` outer electronic configuration. The unpaired electrons do not pair up because of weak field provided by `F^(-)`.

Options

A. Both Assertion and Reason are true and Reason is the correct explanation of Assertion
B. Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
C. Assertion is true but Reason is false
D. Both Assertion and Reason are false

Answer

A

Explanation

In complex `[CoF_(6)]^(3-)`
Oxidation number of Co =+3
Electronic configuration of `Co^(3+)=1s^(2), 2s^(2), 2p^(6), 3s^(2), 3p^(6), 3d^(6)`
In `Co^(3+)`

In `Co^(3+)` number of unpaired electrons is four, and `F^(-)` is the ligand of weak field, hence, it does not paired up electrons of d-orbital. So, `In[CoF_(6)]^(3-)`

So, `[CoF_(6)]^(3-)` is paramagnetic.
`Co^(3+)" has "3d^(6)` outer electronic configuration, but four unpaired electrons do not pair up because of weak field provided by `F^(-)`.