Hi Dinesh,

The correct order of increasing ionization energy of C,N,O & F is C < O < N < F.

The ionization energy increases in a period when moving from left to right. This is due to increase in the effective nuclear charge of elements.

Feel free to ask doubts in the Comment Section.

I hope this information helps you.

Good Luck!

Hello,

Ionization energy is basically defined as the measure of the difficulty in removing an electron from an atom or ion. Ionization energy increases across the period. This is because of the increase in the effective nuclear charge. Therefore, the correct order of ionization energy of C,N,O & F is C<O<N<F.

Hope this helps!