Question

Among the following, the pair in which the two species are not isostructural is:

• A. ${I{O}_3}^{-}$ and $Xe{O}_3$
• B. ${B{H}_4}^{-}$ and $N{H}_4^{+}$
• C. ${P{F}_6}^{-}$ and $S{F}_6$
• D. $Si{F}_4$ and $S{F}_4$

Answer 1

The correct option is D $Si{F}_4$ and $S{F}_4$

Two molecules are iso-structural if they have a similar no. of atoms arranged in a similar structure.

A. ${10}_3^{-}$ and $Xe{O}_3$ are iso structural

${10}_3^{-}7+6\left(3\right)+1=26$ electrons

${10}_3^{-}$ has a trigonal Pyramidal geometry

(Image 1)

$Xe{O}_{3}8+6\left(3\right)=26$electrons

$Xe{O}_3$ has a trigonal Pyramidal geometry

(Image 2)

B. $B{H}_4^{-}$ and $N{H}_4^{+}$ are iso structural

$B{H}_4^{-}3+4\left(1\right)+1=8$ electrons

$B{H}_4^{-}$ has a tetrahedral geometry

(Image 3)

$N{H}_4^{+}5+4\left(1\right)-1=8$ electrons

Even $N{H}_4^{+}$ has a tetrahedral geometry

(Image 4)

C. $P{F}_6^{-}=1+5+7\left(6\right)=48$ electrons

$P{F}_6^{-}$ has a octahedral geometry

(Image 5)

$S{F}_6=6+6\left(7\right)=48$ electrons

$S{F}_6$ also has an octahedral geometry

(Image 6)

D. $Si{F}_4=4+4\left(7\right)=32$electrons

$Si{F}_4$ has a tetrahedral geometry

(Image 7)

$S{F}_4=6+7\left(4\right)=34$ electrons

$S{F}_4$ has a see saw geometry

(Image 8)