A) \[Si{{F}_{4}}\] and \[S{{F}_{4}}\]
B) \[IO_{3}^{-}\] and \[Xe{{O}_{3}}\]
C) \[B{{H}_{4}}\] and \[NH_{4}^{+}\]
D) \[PF_{6}^{-}\] and \[SF_{6}^{{}}\]
Correct Answer: A
Solution :
\[Si{{F}_{4}}\] and \[S{{F}_{4}}\] are not is structural because \[Si{{F}_{4}}\] is tetrahedral due to \[\text{s}{{\text{p}}^{3}}\]hybridisation of Si. |
\[_{14}Si=1{{s}^{2}},2{{s}^{2}},2{{p}^{6}},3{{s}^{2}}3{{p}^{2}}\] (In ground state) |
\[_{14}Si=1{{s}^{2}},2{{s}^{2}},2{{p}^{6}},3{{s}^{2}}3{{p}^{2}}\] (In excited state) |
\[_{14}Si=1{{s}^{2}},2{{s}^{2}},2{{p}^{6}},3{{s}^{1}}3{{p}^{3}}\] (In excited state) |
Hence, four equivalent\[s{{p}^{3}}\]-hybrid orbitals are obtained and they are overlapped by four p-orbitals of four fluorine atoms on their axes. |
Thus it shows following structure : |
While \[S{{F}_{4}}\] is not tetrahedral but it is distorted tetrahedral because in it S is \[s{{p}^{3}}\] d-hybrid. |
\[_{16}S=1{{s}^{2}},2{{s}^{2}}2{{p}^{6}},3{{s}^{2}}3p_{x}^{2}3p_{y}^{1}3p_{z}^{1}\] |
(In ground state) |
\[=1{{s}^{2}},2{{s}^{2}}2{{p}^{6}},3{{s}^{2}}3p_{x}^{1}3p_{y}^{1}3p_{z}^{1,}3d_{xy}^{1}\] |
\[s{{p}^{3}}\] d-hybridisation |
(In first excitation state) |
Hence, five \[s{{p}^{3}}\] d-hybrid orbitals are obtained. |
One orbital is already paired and rest four are overlapped with four p-orbitals of four fluorine atoms on their axis in trigonal bipyramidal form. This structure is distorted from trigonal bi-pyramidal to tetrahedral due to involvement of repulsion between lone pair and bond pair. |
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