The ionisation enthalpy of `Na` is less than `Ne`. Why?

Why is the ionisation enthalpy of oxygen is less than those of nitrogen ad fluorine?

First ionisation enthalpy off Na is less than that of Mg, but second ionisation enthalpy of Na is higher than that of Mg. explain.

The first ionisation enthalpy of Mg is higher than the first ionisation enthalpy of:

Why the bond dissociation enthalpy of F_2 is less than that of Cl_2 .

The ionisation enthalpy of nitrogen is larger than that of oxygen because of:

The first ionisation enthalpy of Mg is higher than that of Na but the second ionisation enthalpy is lower than that of Na -Explain.

Ionisation enthalpy of Na would be same as

Ionisation enthalpy of Na would be same as