A teacher writes the Lewis structures of $\text{BCl}_3$, $\text{SF}_6$ and $\text{NO}_2$ on the board. She asks whether each atom obeys the octet rule. Read two statements made by students. Statement I: Boron in $\text{BCl}_3$ has only six electrons around it, and sulphur in $\text{SF}_6$ has twelve; both are exceptions to the octet rule. Statement II: In $\text{NO}_2$ every atom completes its octet, because the molecule has an even number of valence electrons.