In which of the following crystals are alternate tetrahedral voids occupied:

1. NaCl

2. ZnS

3. CaF2

4. Na2O

Subtopic:  Voids, Radius Ratio & Coordination Number |
 61%
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In a metal oxide, the oxide ions are arranged in hexagonal close packing and metal ions occupy two third of the octahedral voids. The formula of the oxide is : 

1. MO

2. M2O3

3. MO2

4. M2O

Subtopic:  Density & Packing Fraction |
 89%
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The edge length of fcc unit cell of NaCl is 508 pm. If the radius of cation is 110 pm, then the radius of the anion is : 

1. 144 pm

2. 249 pm

3. 288 pm

4. 398 pm

Subtopic:  Introduction & Crystal System | Voids, Radius Ratio & Coordination Number |
 60%
From NCERT
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A crystal is made of particle X, Y & Z. X forms FCC packing, Y occupies all octahedral

voids of X and Zoccupies all tetrahedral voids of X, if all the particles along one body

diagonal is removed then the formula of the crystal would be –

(1) XYZ2

(2) X2YZ2

(3) X5Y4Z5

(4) X5Y4Z8

Subtopic:  Density & Packing Fraction |
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In a hypothetical solid C atoms are found to form cubical close packed lattice. Aatoms occupy all tetrahedral vioids& B atoms occupy all octahedral voids. A and B atoms are of appropriate size, so that there is no distortion in CCP lattice of C atoms. Now if a plane as shown in the following figure is cut.

Then the cross section of this plane will look like.

(1)

(2)

(3)

(4)

Subtopic:  Voids, Radius Ratio & Coordination Number |
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In hexagonal close packing of sphere in three dimensions.

(1) In one unit cell there are 12 octahedral voids and all are completely inside the unit cell.

(2) In one unit cell there are six octahedral voids and all are completely inside the unit cell.

(3) In one unit cell there are six octahedral void and of which three are completely inside the unit cell and other three are partially inside the unit cell.

(4) In one unit cell there are 12 tetrahedral voids, all are completely inside the unit cell.

Subtopic:  Density & Packing Fraction |
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Diamond has face-centred cubic lattice. There are two atoms at (0,0,0) and 14,14,14coordinates.The ratio of the carbon-carbon bond distance to the edge of the unit cell is

(1) 316

(2) 4

(3) 14

(4) 12

Subtopic:  Density & Packing Fraction |
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Spinel is an important class of oxides consisting of two types of metal ions with the oxide ions arranged inCCP pattern. The normal spinel has 1/ 8 of the tetrahedral holes occupied by one type of metal ion and 1/2 of the octahedral holes occupied by another type of metal ion. Such a spinel is formed by Zn2+, A13* and 02-with Zn2+ in the tetrahedral holes. If CCP arrangement of oxide ions remains undistorted in the presence of all the cations, formula of spinel and fraction of the packing fraction of crystal are respectively :

(1) ZnAl2O4 , 77%

(2) ZnAl2O4, 74%

(3) Zn2AlO4, 74%

(4) Zn3Al2O6,74%

Subtopic:  Introduction & Crystal System |
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What is the maximum number of layers of atoms in close-packed planes that will lie within two imaginary parallel planes having a distance between them of 1323 R (where R is the radius of an atom) in the copper crystal (FCC)?
Consider the atoms to be within the parallel planes if their centers are on or within the two parallel planes.

1. 5

2. 6

3. 7

4. 8

Subtopic:  Introduction & Crystal System |
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Analysis show that nickel oxide consist of nickel ion with 96% ions having d8 configuration and 4% having d7 configuration. Which amongst the following best represents the formula of the oxide.

(1) Ni1.02O1.00

(2) Ni0.96O1.00

(3) Ni0.96O0.98

(4) Ni0.98O1.00

Subtopic:  Density & Packing Fraction |
 54%
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