Assertion : In NaCl crystal each Na ion is touching 6 Cl ions but these Cl ions do not touch each other.

Reason : The radius ratio roe rNa/rCl- is greater than 0.414, required for exact fitting.

  1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
  3. If the assertion is true but the reason is false
  4. If both the assertion and reason are false

Concept Questions :-

Voids and radius ratio/coordination number
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Assertion : The ratio of Zn2+ and F- per unit cell of ZnS and CaF2 is 1:2. 

Reason : In ZnS Zn2+ ions occupy alternate tetrahedral voids and in CaF2 F- ions occupy all the tetrahedral voids of FCC unit cell.

 

  1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
  3. If the assertion is true but the reason is false
  4. If both the assertion and reason are false

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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Difficulty Level:


Sodium metal crystallizes in bcc lattice with cell edge =4.29 A0. The radius of sodium atom will be-

(A) 1.50 A0                                                 

(B) 1.86  A0

(C) 2.80 A0                                               

(D) None of these 

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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The space lattice of graphite is

(A) Cubic                                     

 (B) Tetragonal

(C) Rhombic                                 

(D) Hexagonal

Concept Questions :-

Introduction and Type of Crystal System
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The edge length of cube is 400pm. Its body diagonal would be-

(A) 500 pm                                         

 (B) 693 pm

(C) 600 pm                                           

(D) 566pm

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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A metallic element exists as cubic lattice. Each edge of the unit cell is 2.88 A0. The density of the metal is 7.20 g cm-3. How many unit cell will be present in 100 g of the metal -

(A) 6.85×102                             

(B) 5.82×1023

(C) 4.37×105                             

(D) 2.12×106

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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Iron crystallizes in a b.c.c. system with a lattice parameter of 2.861 A0. Calculate the density of iron in the b.c.c. system (Atomic weight of Fe = 56, NA=6.02×1023mol-1)

(A) 7.92g ml-1                                   

 (B) 8.96g ml-1

(C) 2.78g ml-1                                     

(D) 6.72g ml-1

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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An alloy of copper, silver and gold is found to have copper constituting the ccp lattice. If silver atoms occupy the edge centres and gold is present at body centre, the alloy has a formula-

(A) Cu4Ag2Au                               

(B) Cu4Ag4Au

(C) Cu4Ag3Au                               

(D) CuAgAu

Concept Questions :-

Density/Formula/packing fraction/ Semiconductors
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Frenkel defect is not found in the halides of alkali metals because alkali metals have

1. high electropositivity

2. high ionic radii

3. high reactivity

4. ability to occupy interstitial sites

Concept Questions :-

Voids and radius ratio/coordination number
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Iodine crystal are-

(A) Metallic solid                                       

(B) Ionic solid

(C) Molecular solid                                   

(D) Covalent solid

Concept Questions :-

Introduction and Type of Crystal System
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Difficulty Level: