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 $Li<B<Be<C<O<N<F<Ne$

As we go from left to right in a period ionisation energy increases. $Be$ and $N$ comparatively more stable valence subshell than $B$ and $O$ respectively.

Hence, the correct order of first ionisation enthalpy is:

$Li<B<Be<C<O<N<F<Ne$