Answer:
[tex]\boxed{\text{BF}_{3}}[/tex]
Explanation:
You must draw the Lewis structure for each molecule, trying to give every atom an octet.
In the structures below, every molecule except one has a central atom with octet. That molecule is
[tex]\boxed{\textbf{BF}_{3}}[/tex]
The B atom has only six electrons in its valence shell, so it violates the octet rule.
