question_answer

In which of the following molecules the central atom does not have sp3 hybridisation?  [AIPMT (M) 2010]

A)  \[C{{H}_{4}}\]       

B)  \[S{{F}_{4}}\]

C)  \[BF_{4}^{-}\]           

D)       \[NH_{4}^{+}\]

Correct Answer: B

Solution :

           

When the number of hybrid orbitals, H is 4, the hybridization is sp3.

\[H=\frac{1}{2}[V+M-C+A]\] where, V = number of valence electrons of central atom

M = number of monovalent atoms

C = total positive charge

A = negative charge

[a]\[C{{H}_{4}},\]

\[H=\frac{1}{2}[4+4-0+0]=4,\]thus \[s{{p}^{3}}\]hybridization

[b] For\[S{{F}_{4}},\]

\[H=\frac{1}{2}[6+4-0+0]=5,\]thus

Hybridization

[c] For \[BF_{4}^{-},\]

\[H=\frac{1}{2}[3+4-0+1]=4,\]thus\[s{{p}^{3}}\]

Hybridization

[d] For\[NH_{4}^{+},\]

\[H=\frac{1}{2}[5+4-1+0]=4,\]thus\[s{{p}^{3}}\]

Hybridization

Thus, only in \[S{{F}_{4}},\] the central atom does not have sp3 hybridization.