The pair having the same magnetic moment is :
(Atomic Nos : `Cr=24`, `Mn=25`, `Fe=26`, `Co=27`) [ M n ( H 2 O ) 6 ] 2 + & [ C r ( H 2 O ) 6 ] 2 + [ C o C l 4 ] 2 − & [ F e ( H 2 O ) 6 ] 2 + [ C r ( H 2 O ) 6 ] 2 + & [ C o C l 4 ] 2 − [ C r ( H 2 O ) 6 ] 2 + & [ F e ( H 2 O ) 6 ] 2 +

Options

A. `[Cr(H_2O)_6]^(2+) and [CoCl_4]^(2-)`
B. `[Cr(H_2O)_6]^(2+)and [Fe(H_2O)_6]^(2+)`
C. `[Mn(H_2O)_6]^(2+) and [Cr(H_2O)_6]^(2+)`
D. `[CoCl_4]^(2-) and [Fe(H_2O)_6]^(2+)`

Answer

B

Explanation

Thus, `[Cr(H_2O)_6]^(2+) and [Fe(H_2O)_6]^(2+)` have the same number of unpaired electrons and hence have same magnetic moment.