Voids in Lattice

IMPORTANT

Voids in Lattice: Overview

This topic covers concepts, such as, Voids and Their Types, Octahedral and Tetrahedral Voids, Number and Locations of Tetrahedral and Octahedral Voids in FCC, Triangular Planar Voids & Cubical Voids etc.

Important Questions on Voids in Lattice

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IMPORTANT

The distance between an octahedral and a tetrahedral void in pm in FCC lattice would be: 

(Consider edge length is 7 pm)

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Column I (Type of crystal) Column II (Location of cations/anions) 
(A) NaCl  (p) Cations-fcc, Anions-all tetrahedral voids 
(B) ZnS (q) Anions-fcc, Cations-all tetrahedral voids
(C) CaF2 (r) Anions-fcc, Cations-all octahedral voids
(D) Na2O (s) Anions-fcc, Cations-alternate tetrahedral voids

 

MEDIUM
IMPORTANT

A molecule have radius ratio of r-r+ is more than 0.732. Which of the following void is presented in the molecule.

EASY
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A molecule have radius ratio of r-r+ is 0.200 . Which of the following void is presented in the molecule.

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The radius ratio of triangular planar radius is r+r-=

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Right option for the number of tetrahedral and octahedral voids in hexagonal primitive unit cell are:

HARD
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In a compound, atoms of element Y form cubic close packing lattice and those of element X occupy23 times  of tetrahedral voids. The formula of the compound will be

MEDIUM
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Octahedral voids are formed when the triangular voids in second layer exactly overlap with similar voids in the first layer.

EASY
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The total number of tetrahedral voids in the face centred unit cell is

MEDIUM
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In a carbon allotrope having FCC lattice, two atoms are at 0, 0, 0 and a8, a8, a8 coordinates. What is the ratio of C-C bond length distance to the edge length of the unit cell?

MEDIUM
IMPORTANT

 In a compound, oxide ions are arranged in cubic close packing arrangement. Cations A occupy 1/6 of the tetrahedral voids and cations B occupy 1/3 of the octahedral voids. The formula of the compound is
 

EASY
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For the structure given below the site marked as S is a :-

Question Image

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An ionic compound is expected to have a tetrahedral structure if r+/r- lies in the range of

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The total number of tetrahedral voids in the face-centred unit cell is _____.

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The number of tetrahedral sites per sphere in ccp structure is,

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The number of octahedral sites per sphere in fcc structure is

EASY
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The ratio of close packed atoms to octahedral holes in hexagonal close packing is

EASY
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The ratio of close packed atoms to tetrahedral holes in cubic packing is

MEDIUM
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In a solid XY, having the rock salt structure, Y atoms form the FCC arrangement and X atoms occupy all the octahedral voids. If the X atom at body centred octahedral void is missing, then the formula of the compound will be:

MEDIUM
IMPORTANT

In a face centred cubic arrangement of metallic atoms, what is the relative ratio of the sizes of tetrahedral and octahedral voids?