question_answer

.In which of the following pairs, both the species are not isostructural?                        [NEET 2015 (Re)]

A)  \[SiC{{l}_{4}},PCl_{4}^{+}\]        

B)       Diamond, carbide

C)  \[N{{H}_{3}},P{{H}_{3}}\]          

D)       \[Xe{{F}_{4}},Xe{{O}_{4}}\]

Correct Answer: D

Solution :

(i) Structure of \[\text{SiC}{{\text{l}}_{\text{4}}}\]

Structure of \[\text{PCl}_{\text{4}}^{\text{+}}\]

(ii) Diamond and silicon carbide (SiC), both are isostructural because their central atom is \[s{{p}^{3}}\]

hybridised and both have tetrahedral arrangement.

(iii) Structure of \[N{{H}_{3}}\]

Structure of \[P{{H}_{3}}\]

Both \[N{{H}_{3}}\] and \[P{{H}_{3}}\] have \[s{{p}^{3}}\] geometry.

(iv) \[Xe{{F}_{4}}\] has \[s{{p}^{3}}{{d}^{2}}\] hybridisation while \[Xe{{O}_{4}}\] has \[s{{p}^{3}}\] hybridisation.

Structure of \[Xe{{F}_{4}}\]

Structure of \[Xe{{O}_{4}}\]

Hence, \[Xe{{F}_{4}}\] and \[Xe{{O}_{4}}\] are not isostructural.