Question

For the second period elements, the correct increasing order of first ionisation enthalpy is:

• A. $Li<Be<B<C<N<O<F<Ne$
• B. $Li<B<Be<C<O<N<F<Ne$
• C. $Li<B<Be<C<N<O<F<Ne$
• D. $Li<Be<B<C<O<N<F<Ne$

Answer 1

The correct option is B $Li<B<Be<C<O<N<F<Ne$

Both $Be$ and $N$ have comparatively more stable sub-shells than $B$ and $O$.
Thus the correct order of first ionisation enthalpy is:
$Li<B<Be<C<O<N<F<Ne$