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Question Bank No: 1

1. An element (at. Mass=100) having bcc structure has unit cell edge 400pm. The density of the element is

a)		10.376 g/ ${cm}^{3}$
b)		5.1888 g/ ${cm}^{3}$
c)		7.289 g/ ${cm}^{3}$
d)		2.144 g/ ${cm}^{3}$

2. The number of atoms in 100 g of fcc crystal with density (d)= 10 g ${cm}^{- 3}$ and edge length 200 pm is equal to

a)		3 $\times 10^{25}$
b)		5 $\times 10^{24}$
c)		1 $\times 10^{25}$
d)		2 $\times 10^{25}$

3. In a compound XY2O4, oxide ions are arranged in CCP and cations X are present in octahedral voids. cations Y are equally distributed between octahedral and tetrahedral voids. What fraction of the total voids is occupied by X and Y?

a)		1/2
b)		1/4
c)		1/6
d)		1/8

4. In a solid, oxide ions are arranged in CCP arrangement. Cations A occupy one-sixth of the tetrahedral voids and cations B occupy one-third of the octahedral voids. The formula of the compound is

a)		AB $O_{3}$
b)		A $B_{2} O_{3}$
c)		$A_{2} B O_{3}$
d)		$A_{2} B_{2} O_{3}$

5. Which of the following is a ferromagnetic compound?

a)		F $e_{2} O_{3}$
b)		F $e_{3} O_{4}$
c)		C $r_{2} O_{3}$
d)		Cr $O_{2}$

6. Density of a crystal is given by the formula

a)		$\frac{a^{3} M}{z N_{0}}$
b)		$\frac{N_{0} M}{z a^{3}}$
c)		$\frac{zM}{a^{3} N_{0}}$
d)		$\frac{a^{3} N_{0}}{z \times M}$

7. The number of octahedral and tetrahedral voids per sphere in a cubic close packed arrangement is repectively

a)		1 and 3
b)		6 and 4
c)		1 and 2
d)		2 and 1

8. Sodium crystallizes in body centred cubic lattice, the edge length of unit cell being 424 pm. The density will be

a)		0.97 g ${cm}^{- 3}$
b)		1.24 g ${cm}^{- 3}$
c)		0.86 g ${cm}^{- 3}$
d)		1.00 g ${cm}^{- 3}$

9. In a binary compound having cubic unit cell, the anions B are located at the corners of the cube and face centers whereas cations A occupy all the tetrahedral voids. The formula of the compound would be

a)		AB
b)		A $B_{2}$
c)		A $B_{3}$
d)		$A_{2} B$

10. The radius of Na is 95 pm and that of Cl is 181 pm. The edge length of unit cell in NaCl would be

a)		181 pm
b)		95 pm
c)		276 pm
d)		552 pm

11. The percentage of the available space occupied in a hexagonal close packing of spheres in three dimensions is

a)		26%
b)		74%
c)		52.4%
d)		76%

12. Aluminium adopts fcc arrangement of close packing. The number of aluminium atoms per unit cell is

a)		1
b)		2
c)		3
d)		4

13. Monoclinic crystal has dimensions of

a)		a $\neq b \neq c, α = γ = 90^{0}, β \neq 90^{0}$
b)		a = b = c, $α + β = γ = 90^{0}$
c)		a =b $\neq c, α = β = γ = 90^{0}$
d)		a $\neq b \neq c, α \neq γ \neq 90^{0}$

14. CsBr crystal has bcc structure. It has an edge length of 4.3 $\overset{0}{A .}$ the shortest distance between Cs and Br ions is

a)		3.72 $\overset{0}{A}$
b)		4.3 $\overset{0}{A}$
c)		1.86 $\overset{0}{A}$
d)		7.44 $\overset{0}{A}$

15. A crystal lattice with alternate +ve and -ve ions has radius ratio of 0.54. Its coordination number is

a)		4
b)		3
c)		6
d)		12

16. A semiconductor of Ge can be made p-type by adding

a)		trivalent impurity
b)		tetravalent
c)		pentavalent impurity
d)		divalent impurity

17. The interionic distance for cesium chloride crystals will be

a)		a
b)		$a / 2$
c)		$\sqrt{3} a / 2$
d)		$2 a \sqrt{3}$

18. Which of the following crystals does not exhibit Frenkel defect?

a)		AgBr
b)		AgCl
c)		KBr
d)		ZnS

19. Body centered cubic lattice has a coordination number

a)		8
b)		12
c)		6
d)		4

20. The number of NaCl molecules in unit cell of its crystal is

a)		2
b)		4
c)		6
d)		8

21. An element (atomic mass = 100 g/mol) having bcc structure has unit cell edge 400 pm. The density of the element is

a)		10.376 g/c $m^{3}$
b)		5.1888 g/c $m^{3}$
c)		7.289 g/c $m^{3}$
d)		2.144 g/c $m^{3}$

22. Which of the following describes the hexagonal close packed arrangement of spheres?

a)		ABCABA
b)		ABC ABC
c)		ABABA
d)		ABBABB

23. Ionic solids with Schottky defects contain in their structure

a)		equal number of cation and anion vacancies
b)		interstitial anions and anion vacancies
c)		cation vacancies only
d)		cation vacancies and interstitial cations