The number of d electrons retained in Fe^{2+} (At. no. Fe = 26) ions is

- 3
- 4
- 5
- 6

**Answer**

^{26}Fe = 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{6} 4s^{2}

Fe^{++} = 1s^{2} 2s^{2} 2p^{6} 3s^{2} 3p^{6} 3d^{6}

The number of d electrons retained in Fe^{2+} = 6

**The correct option is D.**