Chemistry - Solid State Question with Solution | TestHub

ChemistrySolid StateVoids or Interestitial SitesHard2 minQB

ChemistryHardsingle choice

An ionic solid of formula $MX_{2}$ has radius ratio $r_{M^{2 +}} / r_{X^{-}}$ = 0.30. The structure of its unit cell is:

Answer:

Solution:

Radius ratio 0.225 - 0.414 means tetrahedral voids (coordination number 4). This rules out the cubic void (A) and octahedral void (C).

Stoichiometry: fcc $X^{-}$ has 4 $X^{-}$ and 8 tetrahedral voids. $MX_{2}$ needs 2 $M^{2 +}$ per 4 $X^{-}$ , so 2 of 8 voids = 25%: (B) holds.

(D) Filling all tetrahedral voids of hcp $X^{-}$ (2 $X^{-}$ , 4 voids) gives $M_{4} X_{2}$ = $M_{2} X$ : false.

Answer: (B).

Stream:JEESubject:ChemistryTopic:Solid StateSubtopic:Voids or Interestitial Sites

⏱ 2mℹ️ Source: QB

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