Answer:
[tex]BF_{3}[/tex] has an atom with incomplete octet
Explanation:
H atoms are generally excluded from octet rule as H atom has only one 1s orbital which can contain maximum two electrons.
At first, lewis structures of all molecules should be drawn. Then octet of an atom is determined by taking summation of all nonbonding electrons along with all bonding electrons corresponding to that atom.
If this summation is less than 8 then it is said that the atom has incomplete octet.
In [tex]BF_{3}[/tex], B atom has no nonbonding electons (i.e. lone pair). B atom is attached to three F atoms via three single bonds. Then total number of electrons corresponding to B atom are 6 ( one bond contains two electrons).
All other atoms (except H) in given molecules has complete octet.
So, [tex]BF_{3}[/tex] has an atom with incomplete octet.
Lewis structures are shown below.
