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An

AB 2 type structure is found in a. Nacl b. Al2 O 3 c. CaF 2 d. N 2 O Ans. c (5)

If ‘Z’ is the number of atoms in the unit cell that represents the closest packing sequence — A B C A B C —, the number of tetrahedral voids in the unit cell is equal to

a. Z b. 2 Z c. Z/2 d. Z/4 Ans. b Explanation : Number of tetrahedral voids in the unit cell = 2 x number of atoms = 2 Z (9)

The arrangement ABC ABC ABC…. is referred as

a. Octahedral close packing b. Hexagonal close packing c. Tetragonal close packing d. Cubic close packing Ans. d Explanation : It represents ccp arrangement (8)

The vacant space in bcc lattice cell is

a. 26 % b. 48 % c. 23 % d. 32 % Ans. d Explanation : Packing efficiency in bcc lattice = 68 % vacant space in bcc lattice = 100- 68 = 32 % (7)

In a solid ‘AB’ having the NaCl structure ‘A’ atoms occupy the corners of the cubic unit cell. If all the face centered atoms along one of the axes are removed, then the resultant stoichiometry of the solid is

a. AB2 b. A 2 B c. A4 B 3 d. A 3 B 4 Ans. d (30)

In CsCl structure the coordination number of

Cs + is a. Equal to that of Cl – , that is 6 b. Equal to that of Cl – , that is 8 c. Not Equal to that of Cl – , that is 6 d. Not Equal to that of Cl – …

Which of the following statements is not true about NaCl structure

a. Cl– ions are in fccarrangement b. Na+ ions has coordination number 4 c. Cl– ions has coordination numnber 6 d. Each unit cell contains 4NaCl molecules Ans. b (17)

What is the coordination number in a square close packed structure in two dimensions

a. 2 b. 3 c. 4 d. 6 Ans. c (16)

In which of the following structures coordination number for cations and anions in the packed structure will be same

a. Cl – ions form fcc lattice and Na+ ions occupy all octahedral voids of the unit cell b. Ca 2+ ions form fcc lattice and F – ions occupy all the eight tetrahedral voids of the unit cell c. O 2- ions …

The ionic radii of

Rb+ and I– are 1.46 Å and 2.16 Å . The most probable type of structure exhibited by it is a. CsCl type b. Zns type c. NaCl type d. CaF type Ans. c (26)

In Zincblende structure, zinc atom fill up

a. All octahedral holes b. All tetrahedral holes c. Half number of octahedral holes d. Half number of tetrahedral holes Ans. d Explanation : In zinc blende half number of tetrahedral holes are filled bu zinc atoms. (29)

The ionic radii of

A+and B– ions are 0.98 x 10-10 m and 1.81 x 10 m-10 . The coordination number of each ion in AB is a. 6 b. 4 c.8 d. 2 Ans. a (35)

Postassium has a bcc structure with nearest neighbour distance 4.52 Å . Its atomic weight is 39. Its denstiy will be

a. 454 b. 804 c. 852 d. 908 Ans. d (8)

The cubic unit cell of a metal (molar mass =

63. 55g mol -1 ) has an edge length of 362 pm. Its denstiy is 8.92g cm -3 . The type of unit cell is a. Primitive b. Face centered c. Body centered d. end centered Ans. b (19)

A metal has a fcc lattice. The edge length of the unit cell is 404 pm. The density of the metal is

2.72 g cm -3 . The molar mass of the metal is a. 20 g mol -1 b. 40g mol -1 c. 30 g mol -1 d. 28 g mol -1 Ans. d (7)

An element crtstallising in body centred cubic lattice has an edge lengths of 500 pm. If its density is 4 g cm ^-3, the atomic mass of the element is

a. 100 b. 250 c. 125 d. 150 e. 50 Ans. d (9)

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

a. 10.376 g/cm3 b. 5.188 g/ cm3 c. 7.289 g/cm3 d. 2.144 g/cm3 Ans. b (9)

Lithium has a bcc structure .Its density is 530 kg m ^-3 and its atomic mass is 6.94 g mol ^ -1 Calculate the edge length of a unit cell of Lithium metal.

a. 154 pm b. 352 pm c. 527 pm d. 264 pm Ans. b (18)

Ferrous oxide has a cubic structure and each edge of the unit cell is

50 Å . Assuming density of the oxide as 4.0g – cm -3 then the number of Fe2+ and O2- ions present in each unit cell will be a. Four Fe2+ and four O2- b. Two Fe2+ and four O2- …

The second order Bragg’s diffraction of X – rays with

λ = 1 Å from a set of parallel planes in a metal occurs at an angle of 60º . The distance between the scattering planes in the crystal is a. 0.575 Å b. 1.00 Å c. 2.00Å d. 1.15 …

Percentage of the free space in cubic close packed structure and in body centered packed structure are respectively

a. 48 % and 26 % b. 30 % and 26 % c. 26 % and 32 % d.32% and 48 % Ans. c (11)

The edge length of unit cell of a metal having molecular weight 75g/mol is

5 Å which crystallize in cubic lattice. If the density is 2g/ cc then find the radius of metal atoms. (N A = 6 x 10 23 ) Give the answer in pm a. 217 pm b. 210 pm c. 220 …

How many unit cells are present in a cubic shaped ideal crystal of NaCl of mass 1.00g [ Atomic masses : Na = 23, Cl = 35.5]

a. 2.57 x 10 21 unit cells b. 5. 14 x 1021 unit cells c. 1.28 x 10 21 unit cells d. 1. 71 x 1021 unit cells Ans. a (5)

In orthorhombic, the value of a, b and c are respectively

4.2 Å 8.6 Å and 8.3 Å given the molecular mass of the solute is 155 g mol -1 and that of density is 3.3 g/ cc, the number of formula units per unit cell is a. 2 b. 3 c. …

The pyknometric density of sodium chloride crystal is

2.165 x 103 kg m -3 while its X – rays density is 2.178 x 103 kg m -3 . The fraction of unoccupied sites in sodium chloride crystal is a. 5. 96 x 10-3 b. 5.96 c. 5.96 x 10-2 d. …

When an electron in an excited Mo atom fall from L to K shell; an X- ray is emitted. These X-rays are diffracted at angles of 7.75° by planes with a separation of

2.64Å. What is the difference in energy between K- shell an L – shell in Mo assuming a first-order diffraction (sin 7.75° = 0.1349) a. 36.88 x 10-19 j b. 27.88 x 10 10-16 j c. 63. 88 x 10 10-17 …

To obtain a diffraction peak, for a crystalline solid with inter plane distance equal to the wavelength of incident X-ray radiation, the angle of incidence should be

a. 90° b. 0° c. 30° d. 60 ° Ans. c (6)

If the angle of incidence of X-ray of wavelength 3 Å which produces a second order diffracted beam from the (100) plane in a simple cubic lattice with interlayer spacing a = 6 Å is 30°, the angle of incidence that produce a first order diffracted beam from the (200) planes is

a. 15° b. 45° c. 30° d. 60° Ans. c (16)

10 mL of 1 m M surfactant solution forms a monolayer convering 0.24 cm^2 on a polar substance. If the polar head is approximated as a cube, which is its edge length

a. 1.0 pm b. 2. 0 nm c. 0.1 nm d. 2.0 pm Ans. d (24)

An element has a face-centred cubic (fcc) structure with a cell edge of a. The distance between the centres of two nearest tetraheadral voids in the lattice is

a. √2a b. a c. 3/2 (a) d. a/2 Ans. d Explanation : Nearest distance between tetrahedral voids in a fcc lattice is a/2 (42)

The correct statement for the molecule,

Csl 3 , is a. It is covalent molecule b. it contains Cs3+ and I –3 c. It contains Cs+ and I –3 ions d. It contains Cs+ , I – and lattice I – molecule Ans. b (13)

Which of the following statements is correct for CsBr3

a. It is covalent compound b. it contains Cs3+ and Br – ions c. It contains Cs+ and Br3– ions d. It contains Cs+ , Br– and lattice Br 2 molecule Ans. c (6)

KCl crystallises in the same type of lattice as does NaCl. Given that

r Na + / r Cl – = 0.55 and r k+ / r Cl– = 0. 74. Calculate the ratio of the side of the unit cell for KCl to that of NaCl a. 1.123 b. 0.891 c. 1.414 …

If the unit cell of a mineral has cubic close packed array of oxygen atoms with m fraction of octahedral holes occupied by aluminium ions and n fraction of tetrahedral holes occupied by magnesium ions, m and n respectively are

a. 1/2 , 1/ 8 b. 1 , 1/4 c. 1/2 , 1/ 2 d. 1/4 , 1/ 8 Ans. a (8)

A metal crystallizers into a lattice containing a sequence of layers of atoms of ABABAB… What percentage by volume of this lattice has empty space

a. 74 b. 26 c. 20 d. 16 Ans. b Explanation : ABAB… is hexagonal close packing in which space occupied = 74 % and empty space = 26 (5)

Structure of a mixed oxide is cubic close- packed . The cubic unit cell of mixed oxide is composed of oxide ions. One fourth of the tetrahedral voids are occupied by a monovalent metal B. The formula of the oxide is

a. ABO 2 b. A 2BO2 c. A2 B3 O4 d. AB 2 O 2 Ans. d (15)

If Agl crystallises in zinc blende structure with

I– ions at lattice points. What fraction of tetrahedral voids is occupied by Ag + ions a. 25 % b. 50 % c. 100 % d. 75 % Ans. b (4)

In a compound atoms of Y form ccp lattice and those of element X occupy 2/3rd of tetrahedral voids. The formula of the compound will be

a. X2 Y3 b. X2 Y c. X 3 Y 4 d. X 4 Y 3 Ans. d (7)

The

Ca2+ and F – are located in CaF 2 crystal respectively at face centred cubic lattic points and in a. Tetrahedral voids b. Half of tetrahedral voids c. Octahedral voids d. Half of octahedral voids Ans. a (6)