VJ – 12th CHEMISTRY UNIT 6 - SOLID STATES

UNIT 6 - SOLID STATES

STD – XII TEST – 1 Maximum marks: 35
Portion – 6.1 General characteristics of solids to 6.6.3 Simple cubic arrangement Time – 45 min
I) Answer all the questions. 5 X1 = 5
1. Solid CO2 is an example of
a) Covalent solid b) metallic solid c) molecular solid d) ionic solid
2. The fraction of total volume occupied by the atoms in a simple cubic is
a) b) c) d)
3. Potassium has a bcc structure with nearest neighbor distance 4.52 Å . Its atomic weight is 39. its
density will be
a) 915 kg m-3 b) 2142 kg m-3 c) 452 kg m-3 d) 390 kg m-3
4. The arrangement of crystallographic axes and angles respectively in hexagonal crystal systems is
a) a≠b≠c and 𝛼 = 𝛽 = 𝛾 = 90°, 𝛽 ≠ 90 b) a =b≠c and 𝛼 ≠ 𝛽 ≠ 𝛾 = 90°
c) a =b≠c and 𝛼 = 𝛽 = 90° , 𝛾 = 1200 d) a =b=c and 𝛼 ≠ 𝛽 ≠ 𝛾 = 90°
5. In the simple cubic unit cell, the radius is related to the edge length (a) of the unit cell by -----

a) b) c) d)

II. Answer any four questions. 4X2=8

6. Define unit cell.
7. Why ionic crystals are hard and brittle?
8. What is meant by the term “coordination number”? What is the coordination number of atoms in a bcc
structure?
9. What are Ionic crystals? Give an example.
10. Define Crystal lattice
11. What is meant by packing efficiency (or) fraction? How is measured?
III. Answer any four questions. 4 X 3 = 12
12. Give any three characteristics of ionic crystals.
13. Calculate the number of atoms in an FCC unit cell.
14. Distinguish b/w isotropy and anisotropy in solid
15. Explain briefly seven types of unit cell.
16. What are general characteristics of solids
17. Define covalent solids. Give the examples
IV. Answer any two questions 2 X 5 = 10
18. Differentiate crystalline solids and amorphous solids.
19. What are molecular crystals? How are they classified? Explain.
20. Calculate the packing efficiency of simple cubic.
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VJ – 12th CHEMISTRY UNIT 6 - SOLID STATES
UNIT 6 - SOLID STATES
STD – XII TEST – 2 Maximum marks: 35
Portion – 6.6.4 Body centered cubic arrangement to 6.7.5 Impurity defect: Time – 45 min
I) Answer all the questions. 5 X1 = 5
1. An ionic compound AxBy crystallizes in fcc type crystal structure with B ions at the centre of each
face and A ion occupying corners of the cube. the correct formula of AxBy is
a) AB b) AB3 c) A3B d) A8B6
2. The ratio of close packed atoms to tetrahedral hole in cubic packing is
a) 1:1 b) 1:2 c) 2:1 d) 1:4
3. In a solid atom M occupies ccp lattice and(1/ 3) 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
4. CsCl has bcc arrangement, its unit cell edge length is 400pm, its inter atomic distance is
a) 400pm b) 800pm c) √3 × 100pm d)
5. When the radius ratios lie between 0.732 and 0.414, the arrangement of the crystal is
a) tetrahedral b) octahedral c) linear d) cubic
II. Answer any four questions. 4X2=8
6. What are point defects?
7. What is the two dimensional coordination number of a molecule in square close packed layer?
8. Sodium metal crystallizes in bcc structure with the edge length of the unit cell 4.3 ×10−8 cm.
Calculate the radius of sodium atom.
9. ZnO is colourless at room temperature but it turns yellow colour on heating, why?
10. What is piezo electricity?
11. What are stoichiometric defects? Give an example.
III. Answer any four questions. 4 X 3 = 12
12. Explain Schottky defect.
13. Explain Frenkel defect
14. Distinguish between hexagonal close packing and cubic close packing.
15. How are point defects classified?
16. Explain “F “centre with a neat diagram.
17. What is Impurity defect?
IV. Answer any two questions 2 X 5 = 10
18. Write a short note on non-stoichiometric defects.
19. Calculate the percentage efficiency of packing in case of body centered cubic crystal.
20. Explain the relationship between atomic radius and edge length of fcc unit cell and calculate its
packing efficiency

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VJ – 12th CHEMISTRY UNIT 6 - SOLID STATES
UNIT 6 - SOLID STATES
STD – XII FULL TEST Maximum marks: 35
Portion – Full portion Time – 45 min
I) Answer all the questions. 5 X1 = 5
1. Graphite and diamond are
a) Covalent and molecular crystals b) ionic and covalent crystals
c) both covalent crystals d) both molecular crystals
−
2. The ionic radii of A and B are 0.98X10 m and 1.81 X 10-10 m. the coordination number of each ion
+ -10

in AB is
a) 8 b) 2 c) 6 d) 4
3. 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
4. The number of close packed spheres is „n‟. The number of tetrahedral voids generated is equal to -----
a) n b) 2n c) 2n2 d) 3n
5. An element (atomic mass = 137.3 g/mol) having bcc structure has unit cell edge 508 pm. The density
of element is
a) 7.289 g/cm3 b) 3.5 g/cm3 c) 10.376 g/cm3 d) 5.188 g/cm3
II. Answer any four questions. 4X2=8
6. What are point defects?
7. What is meant by the term “coordination number”? What is the coordination number of atoms in a
bcc structure?
8. Explain “F “centre with a neat diagram.
9. ZnO is colourless at room temperature but it turns yellow colour on heating, why?
10. If the radius ratio of the compound is b/w 0.225 – 0.414 find out the coordination number and
structure of the compound.
III. Answer any four questions. 4 X 3 = 12
11. Explain Schottky defect.
12. Give any three characteristics of ionic crystals.
13. Distinguish b/w isotropy and anisotropy in solid
14. How are point defects classified?
15. Sketch i.SC ii.BCC iii.FCC & calculate its number of atoms per unit cell
IV. Answer any two questions 2 X 5 = 10
16. Calculate the percentage efficiency of packing in case of body centered cubic crystal.
17. Differentiate crystalline solids and amorphous solids.
18. What are molecular crystals? How are they classified? Explain.

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