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#### Solid State Model Question Paper

12th Standard EM

Reg.No. :
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Chemistry

Time : 01:00:00 Hrs
Total Marks : 40
5 x 1 = 5
1. In a solid atom M occupies ccp lattice and $\left( \cfrac { 1 }{ 3 } \right)$ of tetrahedral voids are occupied by atom N. find the formula of solid formed by M and N.

(a)

MN

(b)

M3N

(c)

MN3

(d)

M3N2

2. CsCl has bcc arrangement, its unit cell edge length is 400pm, its inter atomic distance is

(a)

400pm

(b)

800pm

(c)

$\sqrt { 3 } \times 100pm$

(d)

$\left( \cfrac { \sqrt { 3 } }{ 2 } \right) \times 400pm$

3.  if ‘a’ stands for the edge length of the cubic system ; sc , bcc, and fcc. Then the ratio of radii of spheres in these systems will be respectively

(a)

$\left( \cfrac { 1 }{ 2 } a;\cfrac { \sqrt { 3 } }{ 2 } a;\cfrac { \sqrt { 2 } }{ 2 } a \right)$

(b)

$\left( \sqrt { 1a } :\sqrt { 3a } :\sqrt { 2a } \right)$

(c)

$\left( \cfrac { 1 }{ 2 } a:\cfrac { \sqrt { 3 } }{ 4 } a:\cfrac { 1 }{ 2\sqrt { 2 } } a \right)$

(d)

$\cfrac { 1 }{ 2 } a:\sqrt { 3 } a:\cfrac { 1 }{ \sqrt { 2 } } a$

4. The cation leaves its normal position in the crystal and moves to some interstitial position, the defect in the crystal is known as

(a)

Schottky defect

(b)

F center

(c)

Frenkel defect

(d)

non-stoichiometric defect

5. The crystal with a metal deficiency defect is

(a)

NaCl

(b)

FeO

(c)

ZnO

(d)

KCl

6. 5 x 2 = 10
7. Differentiate crystalline solids and amorphous solids.

8. Distinguish tetrahedral and octahedral voids.

9. What are point defects?

10. Classify the following as amorphous or crystalline solids. Polyurethane, Naphthalene, Benzoic acid, Teflon, Potassium nitrate, Cellophane, Polyvinyl chloride, Fiber glass, Copper.

11. Name an element with which silicon can be doped to give an n-type semi conductor.

12. 5 x 3 = 15
13. Why ionic crystals are hard and brittle?

14. Calculate the percentage efficiency of packing in case of body centered cubic crystal.

15. If NaCI is doped with 10-3 mol % of SrCl2 What is the concentration of cation valencies?

16. Inspite of long range order in the arrangement of particles, why are the crystals usually not perfect?

17. A metallic element exists as a cubic lattice. Each edge of the unit cell is 2.88$\mathring { A }$. The density of the metal is 7.20 g cm-3. How many unit cells there will be in 100g of the metal?

18. 2 x 5 = 10
19. An atom crystallizes in fcc crystal lattice and has a density of 103 gcm−3 with unit cell edge length of 100pm. calculate the number of atoms present in 1 g of crystal.

20. How are crystals classified?