Li < B < Be < C < N < O < F < Ne
Li < Be < B < C < N < O < F < Ne
Li < B < Be < C < O < N < F < Ne
Li< Be < B < C < O < N < F < Ne
Correct option is D. Li < B < Be < C < O < N < F < Ne
As we go from left to right in a period ionisation energy increases. ′Be′ and ′N′ comparatively more stable valence subshell than 'B' and 'O'.Hence, the correct order of first ionisation enthalpy is:Li<B<Be<C<O<N<F<Ne