The electronic configuration of the given elements is as 6C=1s2,2s2,2p2 9F=1s2,2s2,2p5 4Be=1s2,2s2 7N=1s2,2s22p3 10Ne=1s2,2s2,2p6 Thus, Ne has the highest ionisation enthalpy because of its completely filled configuration and high effective nuclear charge.