The correct order of the second ionisation potential of carbon, nitrogen, oxygen and fluorine is

Options

A. `CgtNgtOgtF`
B. `OgtNgtFgtC`
C. `OgtFgtNgtC`
D. `FgtOgtNgtC`

Answer

C

Explanation

(for second ionization potential, `IE_(2)`).
`{:(C-1s^(2)2s^(2)p^(2),C^(+)-1s^(2)2s^(2)p^(1)),(N-1s^(2)2s^(2)p^(3),N^(+)-1s^(2)2s^(2)p^(2)),(O-1s^(2)2s^(2)p^(4),O^(+)-1s^(2)2s^(2)p^(3)),(F-1s^(2)2s^(2)p^(5),F^(+)-1s^(2)2s^(2)p^(4)):}`
As for `IE_(2)` the electron in all the cases is to be removed from 2p orbital so it must follow the order `CltNltOltF` (i.e. increase across a period)
But in case of `O^(+)`, the 2p-orbital is half-filled and is more stable as compared to other. So the order becomes :
`CltNltFltO`.