Question

Electron deficient molecule is

• A. $CCl_4$
• B. $PCl_5$
• C. $BF_3$
• D. $SF_6$

Answer 1

Answer: (C)

$BF_3$

Answer 2

The compounds in which central atom has less than $8$ electrons in their valence shell are electron deficient compounds. (a) $CCl_4Cl - \underset{\overset{|}{C}l}{\overset{\underset{|}{C}l}{C}} - Cl$ Carbon (central atom) has $8$ electrons in valence shell, $4$ from carbon and $1$ electron each from four chlorine atom. Phosphorus (central atom) has $10$ electrons in valence shell, $5$ from $P$ and one each from five chlorine atoms. Boron (central atom) has $6$ electrons in valence shell, $3$ from boron and one each from three fluorine atoms. $\because$ Boron in $BF _{3}$ has less than $8$ electrons. $\therefore$ it is electron deficient molecule and is correct answer. Sulphur (central atom) has $12$ electrons in valence shell, $6$ from sulphur and one each from six fluorine atoms.