Middle of Pyramid - Test # 35

1.

If NaCl is doped with 10^-4 mol % of SrCl₂, the concentration of cation vacancies will be
(N_A = 6.023 x 10²³ mol^-1)
1. 6.023 x 10¹⁵ mol^-1
2. 6.023 x 10¹⁶ mol^-1
3. 6.023 x 10¹⁷ mol^-1
4. 6.023 x 10¹⁴ mol^-1

2.

The edge length of cube is 400pm. Its body diagonal would be-
1. 500 pm
2. 693 pm
3. 600 pm
4. 566 pm

3.

Total volume of atoms present in a face centred cubic unit cell of a metal is -
(r is atomic radius)
1. 20/3 $π$ r³
2. 24/3 $π$ r³
3. 12/3 $π$ r³
4. 16/3 $π$ r³

4.

A solid has a bcc structure. If the distance of closest approach between the two atoms is 1.73 Å, then the edge length of the cell is:
1. 200 pm
2. $\frac{\sqrt{3}}{\sqrt{2}}$ pm
3. 142.2 pm
4. $\sqrt{2}$ pm

5.

Which is covalent solid?
1. Silicate
2. Diamond
3. Graphite
4. All of these

6.

The anions (A) form hexagonal closest packing and atoms (C) occupy only 2/3 of octahedral voids in it. The general formula of the compound is-
1. CA
2. CA₂
3. C₂A₃
4. C₃A₂

7.

Graphite in an example of-
1. Ionic solid
2. Covalent solid
3. Molecular Solids
4. Metallic crystal

8.

Select the correct statement (s)-
(a) The C.N. of cation occupying a tetrahedral hole is 4.
(b) The C.N. of cation occupying a octahedral hole is 6.
(c) In schottky defects, density of the lattice decreases,
1. a,b
2. b,c
3. a,b,c
4. a,c

9.

Which arrangement of electrons leads to anti-ferromagnetism?
1.
2.
3. Both (1) and (2)
4. None of the above.

10.

Among the following types of voids. which one is the largest void:-
1. Triangular system
2. Tetragonal system
3. Monoclinic system
4. Octahedral

11.

The ratio of cations to anion in a closed pack tetrahedral is:
1. 0.714
2. 0.225
3. 0.02
4. none of these

12.

The most efficient packing of similar spheres is obtained in
1. The simple cubic system and the body centered cubic system
2. The simple cubic system and the hexagonal close packed system
3. The face centered cubic system and the hexagonal close packed system
4. The body centered cubic system and the face centered cubic system

13.

Frenkel defect is noticed in:
1. AgBr
2. ZnS
3. Agl
4. All of the above

14.

How many octahedral and tetrahedral holes are present per unit cell in a face centred cubic arrangement of atoms?
1. 8,4
2. 1,2
3. 4,8
4. 2 ,1

15.

Choose the correct matching sequence from the possibilities given

(a) Crystal defect	(i) AB AB AB. . . . type crystal
(b) hcp	(ii) Covalent crystal
(c) CsCl	(iii) Frenkel
(d) Diamond	(iv) Face centered in cube
(e) NaCl	(v) Body centered in cube

	(a)	(b)	(c)	(d)	(e)
(1)	(iii)	(i)	(ii)	(v)	(iv)
(2)	(iii)	(i)	(v)	(ii)	(iv)
(3)	(iii)	(v)	(i)	(ii)	(iv)
(4)	(v)	(iii)	(iv)	(ii)	(i)

16.

Fraction of total volume occupied by atoms in a simple cube is-
1. $π$ /2
2. $\sqrt{3}$ $π$ /8
3. $\sqrt{2}$ $π$ /6
4. $π$ /6

17.

Copper metal has a face-centred cubic structure with the unit cell length equal to 0.361nm. Picturing copper ions in contact along the face diagonal. The apparent radius of a copper ion is-
1. 0.128
2. 1.42
3. 3.22
4. 4.22

18.

An element (atomic mass = 100 g/mole) having a BCC structure has a unit cell edge of 400 pm. The density of the element is :
1. 2.14 g/cm³
2. 5.20 g/cm³
3. 7.28 g/cm³
4. 10.37 g/cm³

19.

The appearance of color in solid alkali metal halides is generally due to:-
1. Frenkel Defect
2. Interstitial Defect
3. F-Centres
4. Schottky Defect

20.

AB crystallizes in a body-centred cubic lattice with edge length a equal to 387 pm. The distance between two oppositely charged ions in the lattice will be :
1. 250 pm
2. 200 pm
3. 300 pm
4. 335 pm

21.

In a face centred cubic lattice, atom A occupies the corner positions and atom B occupies the face
centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is
1.AB₂
2.A₂B₃
3.A₂B₅
4.A₂B

22.

Packing fraction of simple cubic crystal lattice is
1. 38%
2. 74%
3. 68%
4. 52.4%

23.

Silver metal crystallises in a cubic closest – packed arrangement with the edge of the unit cell having a length a = 407 pm. What is the radius of silver atom.
(1) 143.9 pm
(2) 15.6 pm
(3) 11.59 pm
(4) 13.61 pm

24.

From the fact that the length of the side of a unit cell of lithium is 351 pm. Calculate its
atomic radius. Lithium forms body-centered cubic crystals.
(1) 152.69 pm
(2) 62.71 pm
(3) 151.98 pm
(4) 54.61 pm

25.

Lithium borohydride $(L i B H_{4}),$ crystallises in an orthorhombic system with 4 molecules per unit cell. The unit cell dimensions are : a = 6.81Å, b= 4.43Å, c=7.17Å. If the molar mass of $L i B H_{4}$ is 21.76 g mol^–1. The density of the crystal is –
(1) 0.67 g cm^–3
(2) 0.58 g cm^–3
(3) 1.23 g cm^–3
(4) 6.68 g cm^–3

26.

CsBr has a (bcc) arrangement and its unit cell edge length is 400 pm. Calculate the interionic distance in CsBr.
(1) 346.4 pm
(2) 643 pm
(3) 66.31 pm
(4) 431.5 pm

27.

The diffraction of barium with X-radiation of wavelength 2.29Å gives a first – order reflection at 30°. What is the distance between the diffracted planes.
(1) 3.29 Å
(2) 4.39 Å
(3) 2.29 Å
(4) 6.29 Å

28.

The vacant space in bcc lattice cell is ;
1. 26%
2. 48%
3. 23%
4. 32%

29.

Copper crystallises in a face-centred cubic lattice with a unit cell length of 361 pm. What
is the radius of copper atom in pm?
1. 128
2. 157
3. 181
4. 108

30.

Lithium metal crystallises in a body centred cubic crystal. If the length of the side of the
unit cell of lithium is 351 pm, the atomic radius of the lithium will be
1. 240.8 pm
2. 151.8 pm
3. 75.5 pm
4. 300.5 pm

31.

If 'a' stands for the edge length of the cubic systems: simple cubic, body centered cubic and face centered cubic, then the ratio of radii of the spheres in these systems will be respectively,
$(a) \frac{1}{2} a : \frac{\sqrt{3}}{4} a : \frac{1}{2 \sqrt{2}} a (b) \frac{1}{2} a : \sqrt{3} a : \frac{1}{\sqrt{2}} a$
$(c) \frac{1}{2} a : \frac{\sqrt{3}}{2} a : \frac{\sqrt{2}}{2} a (d) 1 a : \sqrt{3} a : \sqrt{2} a$

32.

Which of the following statements is not correct?

1.	The fraction of the total volume occupied by the atoms in a primitive cell is 0.48.
2.	Molecular solids are generally volatile.
3.	The number of carbon atoms in an unit cell of diamond is 8.
4.	The number of Bravais lattices in which a crystal can be categorized is 14.

33.

Iron has a body centred cubic unit cell with the cell dimension of 286.65 pm. Density of iron is 7.87 g cm^-3. The value of Avogadro's number based on this data will be -
(Atomic mass of Fe = 56.0 u)
1. 6.04 x 10²³ mol^-1
2. 12.08 x 10²⁴ mol^-1
3. 6 x 10²² mol^-1
4. 6 x 10^-23 mol^-1

34.

Sodium metal crystallizes in bcc lattice with cell edge $= 4.29 \overset{0}{A}$ . The radius of sodium atom will be-
(1) 1.50 $\overset{0}{A}$
(2) 1.86 $\overset{0}{A}$
(3) 2.80 $\overset{0}{A}$
(4) None of these

35.

A metallic element exists as a cubic lattice. Each edge of the unit cell is 2.88 $\overset{0}{A}$ . The density of the metal is 7.20 g $c m^{- 3}$ . How many unit cell will be present in 100 g of the metal -
(1) $6.85 \times 10^{2}$
(2) $5.82 \times 10^{23}$
(3) $4.37 \times 10^{5}$
(4) $2.12 \times 10^{6}$

36.

Fraction of total volume occupied by atoms in a simple cube is-
(A) $\frac{π}{2}$
(B) $\frac{\sqrt{3} π}{8}$
(C) $\frac{\sqrt{2} π}{6}$
(D) $\frac{π}{6}$

37.

Analysis shows that an oxide ore of nickel has formula Ni_0.98O_1.00. The percentage of nickel as Ni³⁺ ions is nearly
1. 2
2. 96
3. 4.08
4. 98

38.

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

39.

A solid PQ have rock salt type structure in which Q atoms are at the corners of the unit cell. If the body centred atoms in all the unit cells are missing, the resulting stoichiometry will be-
(A) PQ
(B) $P Q_{2}$
(C) $P_{3} Q_{4}$
(D) $P_{4} Q_{3}$

40.

8 : 8 co-ordination of CsCl is found to change into 6 : 6
co-ordination on:
(1) applying pressure
(2) increasing temperature
(3) both (a) and (b)
(4) none of these

41.

At room temperature, sodium crystallizes in a body-centered cubic cell with a 4.24 $\overset{0}{A}$ . The theoretical density of sodium is- (Atomic mass of sodium=23.0 g $m o l^{- 1}$ )
(A) $2.05 g c m^{- 3}$
(B) $3.45 g c m^{- 3}$
(C) $1.00 g c m^{- 3}$
(D) $3.55 g c m^{- 3}$

42.

The unit cell dimensions of a cubic lattice (edges a, b, c and the angles between them, α, β, γ) are :
1. a = b = c, $α = β = γ = 90 °$
2. a = b $\neq$ c, $α = β = γ = 90 °$
3. a = b = c, $α = γ = 90 °,$ $β \neq 90 °$
4. a $\neq$ b $\neq$ c, $α = β = 90 °,$ $γ \neq 90 °$

43.

Copper metal has a face-centered cubic structure with the unit cell length equal to 0.361 nm. Picturing copper ions in contact along the face diagonal. The apparent radius of a copper ion is-
(A) 0.128
(B) 1.42
(C) 3.22
(D) 4.22

44.

A compound alloy of gold and copper crystallizes in a cube lattice in which the gold atoms occupy the lattice points at the corners of a cube and the copper atoms occupy the centres of each of the cube faces. The formula of this compound is-
(1) AuCu
(2) $A u C u_{2}$
(3) $A u C u_{3}$
(4) None of these

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