Which particle may be removed from a stable neutral atom with the least energy change?

Ionization energy is highest for

The correct order of $2^{nd}$ ionisation potential of carbon,nitrogen,oxygen and fluorine is

Which of the following electronic configurations represents the element with the lowest ionization energy?

$B$ has a smaller first ionization enthalpy than $Be$. Consider the following statements:
$(I)$ It is easier to remove a $2p$ electron than a $2s$ electron.
$(II)$ The $2p$ electron of $B$ is more shielded from the nucleus by the inner core of electrons than the $2s$ electrons of $Be$.
$(III)$ The $2s$ electron has more penetration power than the $2p$ electron.
$(IV)$ The atomic radius of $B$ is more than $Be$.
(Atomic number: $B=5, Be=4$)
The correct statements are:

Element having highest $I.P.$ value is