Question on Complex ions?

Question

Which of the following complex ions would absorb light with the longest wavelength.

A. [Co(H2O)6](2+)
B. [Co(NH3)6](2+)
C. [CoF6](4-)
D. [Co(CN)6](4-)
E. [Co(en)6](2+)

Answer 1

Absorbing at longest wavelength means having the smallest energy difference in the orbitals.

Thus the correct answer is C since the difference in the energy follows the order below:

F- < H2O < NH3
By the way, you have written E in a wrong way; it should be [Co(en)3](+2) since en is a divalent ligand

Answer 2

The bellerophon is correct! The "en" is a bidentade ligand.

Answer 3

B