Question

Which pair of molecules has same reason of non-existance ?
(I) $IF_{3}^{2 -}$
(II) $H_{4}Se$
(III) $XeF_{4}_{}^{2 -}$
(IV) $NCl_{5}$

• A. $IF_{3}^{2 -},XeF_{4}^{2 -}$
• B. $H_{4}Se,NCl_{5}$
• C. $XeF_{4}^{2 -},H_{4}Se$
• D. $IF_{3}\_{}^{2 -},NCl_{5}$

Answer 1

Answer: (A)

$IF_{3}^{2 -},XeF_{4}^{2 -} \rightarrow l.p.$ are present at $90^\circ ,$ so it is unstable and does not exist. $NCl_{5} \rightarrow $ due to the absence of d-orbital contraction
$H_{4}Se \rightarrow $ Se can not form bond with hydrogen in its excited state.