Which of the following elements has the lowest ionisation potential?

The first ionization enthalpies of $N$ and $O$ are respectively....... $eV$.

$B$ 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:

Which of the following transitions involves the maximum amount of energy?

The second ionisation energies of $Li, Be, B$ and $C$ are in the order

Which electronic configuration shows the minimum first ionisation energy?