$B$ has a smaller first ionization enthalpy than Be. Consider the following statements 

(I) It is easier to remove $2p$ electron than $2s$ electron. 

(II) $2p$electron of $B$ is more shielded from the nucleus by the inner core of electrons than the $2s$ electrons of Be. 

(Ill) $2s$ electron has more penetration power than $2p$ electron 

(IV) Atomic radius of $B$ is more than Be. (Atomic number $B = 5. Be = 4$) 

The correct statements are