Which of the following orders are correct ?

Options

A. `[Fe(CO)_(4)]^(2-) lt [Co(CO)_(4)]^(-) lt [Ni(CO)_(4)] implies` Stretching vibrational frequency of C-O bond
B. `[Mn(CO)_(5)]^(-) lt [Mn(CO)_(6)]^(+) implies` EAN of central metal ion
C. `Trien=imda^(2-) implies " Denticity of ligand "`
D. `[Ni(en)_(3)]^(2+) lt [Ni(NH_(3))_(2)(en)_(2)]^(2+) implies` Number of stereo isomers

Answer

A, D

Explanation

(d) `[Ni(NH_(3))_(2)(en)_(2)]^(2+) implies "trans"`,cis (op. active)