An ionic compound A_x B_y 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 A_xB_y is ________.

(a)

AB

(b)

AB₃

(c)

A₃B

(d)

A₈B₆

In calcium fluoride, having the flurite structure the coordination number of Ca²⁺ ion and F^- Ion are ________.

(a)

4 and 2

(b)

6 and 6

(c)

8 and 4

(d)

4 and 8

The number of carbon atoms per unit cell of diamond is _______.

(a)

8

(b)

6

(c)

1

(d)

4

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)

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

The radius of an atom is 300pm, if it crystallizes in a face centered cubic lattice, the length of the edge of the unit cell is ________.

(a)

488.5pm

(b)

848.5pm

(c)

884.5pm

(d)

484.5pm

Schottky defect in a crystal is observed when ______.

(a)

unequal number of anions and anions are missing from the lattice

(b)

Equal number of cations and anions are missing from the lattice

(c)

an ion leaves its normal site and occupies an interstitial site

(d)

no ion is missing from its lattice

The crystal with a metal deficiency defect is ________.

(a)

NaCl

(b)

FeO

(c)

ZnO

(d)

KCl

In which of the following arrangements, octahedral voids are formed?

(a)

fcc

(b)

bcc

(c)

simple cubic

(d)

hcp

What is the relation between diamond and graphite?

(a)

Polymorphous

(b)

Isomer

(c)

Isotope

(d)

Isomorphous

A regular three dimensional arrangement of identical points in space is called _______.

(a)

Unit cell

(b)

Space lattice

(c)

Primitive

(d)

Crystallography

Impurity defect 

(1)

a≠b≠c, ∝=૪=90^o, β≠90^o

Metal deficiency defect

(2)

NaCl with Sr²⁺ and some cationic sites vacant.

Schottky defect

(3)

NaCI

Schottky defect

(4)

FeO with Fe³⁺

Monoclinic

(5)

NaCI

Define unit cell.

Give any three characteristics of ionic crystals.

Explain briefly seven types of unit cell.

Distinguish tetrahedral and octahedral voids.

What are point defects?

Explain Schottky defect.

Calculate the number of atoms in a fcc unit cell.

Why ionic crystals are hard and brittle?

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

What is the two dimensional coordination number of a molecule in square close packed layer?

If NaCl is doped with 10^-2 mol percentage of strontium chloride, what is the concentration of  cation vacancy?

Atoms X and Y form bcc crystalline structure. Atom X is present at the corners of the cube and Y is at the centre of the cube. What is the formula of the compound?