question_answer

Electron deficient molecule is

A) \[CC{{l}_{4}}\]                  

B)        \[PC{{l}_{5}}\]

C)        \[B{{F}_{3}}\]                                    

D)        \[S{{F}_{6}}\]

Correct Answer: C

Solution :

The compounds in which central atom has less than 8 electrons in their valence shell are electron deficient compounds. (a)\[CC{{l}_{4}}Cl-\underset{\begin{smallmatrix}  | \\  Cl \end{smallmatrix}}{\overset{\begin{smallmatrix}  Cl \\  | \end{smallmatrix}}{\mathop{C}}}\,-Cl\] Carbon (central atom) has 8 electrons in valence shell, 4 from carbon and 1 electron each from four chlorine atom. (b) Phosphorus (central atom) has 10 electrons in valence shell, 5 from P and one each from five chlorine atoms. (c) Boron (central atom) has 6 electrons in valence shell, 3 from boron and one each from three fluorine atoms. \[\because \]Boron in \[B{{F}_{3}}\] has less than 8 electrons. \[\therefore \]It is electron deficient molecule and is correct answer. (d) Sulphur (central atom) has 12 electrons in valence shell, 6 from sulphur and one each from six fluorine atoms.