The correct increasing order of the second ionization enthalpies of C , N , O and F is

Step-by-step solution

The second ionization enthalpy is the energy required to remove an electron from the corresponding monopositive ion. The electronic configurations of the +1 ions are: C ^+ : [ He ] 2s^2 2p^1 N ^+ : [ He ] 2s^2 2p^2 O ^+ : [ He ] 2s^2 2p^3 F ^+ : [ He ] 2s^2 2p^4 Generally, ionization enthalpy increases from left to right as effective nuclear charge increases. However, O ^+ has a highly stable half-filled 2p^3 configuration. Due to this extra stability, the removal of an electron from O ^+ requires more energy than