A correct statement is

Options

A. A) `[Co(NH_(3))_(6)]^(3+)` is paramagnetic
B. B) `[MnBr_(4)]^(2-)` is tetrahedral
C. C) `[CoBr_(2)(en)_(2)]^(-)` exhibits linkage isomerism
D. D) `[Ni(NH_(3))_(6)]^(2+)` is an inner orbital complex.

Answer

A, B

Explanation

(a) `[Co(NH_(3))_(6)]^(2+)`
`""_(27)Co^(2+):[Ar]3d^(7)4s^(0)`

`n=3` ( where n `=` no. of unpaired electrons)
Hence, complex is paramagnetic in nature.
(b) `[MnBr_(4)]^(2-)`
`""_(25)Mn^(2+):[Ar]3d^(5)`

`[CoBr_(2)(en)_(2)]^(-)` exhibit geometrical isomerism.

(d) `[Ni(NH_(3))_(6)]^(2+)`
`""_(28)Ni^(2+):[Ar]3d^(8)`

Both statements (a) and (b) are correct.