Graphite and diamond are ________.

(a)

Covalent and molecular crystals

(b)

ionic and covalent crystals

(c)

both covalent crystals

(d)

both molecular crystals

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 ionic radii of A⁺ and B⁻ are 0.98 x 10^-10 m and 1.81 x 10^-10 m. the coordination number of each ion in AB is ________.

(a)

8

(b)

2

(c)

6

(d)

4

If ‘a’ stands for the edge length of the cubic system sc, bcc, and fcc. Then the ratio of radii of spheres in these systems will be respectively ________.

(a)

\(\left( \frac { 1 }{ 2 } a;\frac { \sqrt { 3 } }{ 2 } a;\frac { \sqrt { 2 } }{ 2 } a \right) \)

(b)

\(\left( \sqrt { 1a } :\sqrt { 3a } :\sqrt { 2a } \right) \)

(c)

\(\left( \frac { 1 }{ 2 } a:\frac { \sqrt { 3 } }{ 4 } a:\frac { 1 }{ 2\sqrt { 2 } } a \right) \)

(d)

\(\frac { 1 }{ 2 } a:\sqrt { 3 } a:\frac { 1 }{ \sqrt { 2 } } a\)

Which one of the following crystal has 8 : 8 structure?

(a)

MgF₂

(b)

CsCl

(c)

KCl

(d)

NaCl

Calculate the number of atoms in a cubic unit cell having one atom on each corner and one atom on each body diagonal _______.

(a)

2

(b)

3

(c)

4

(d)

5

The number of octahedral void(s) per atom present in a cubic close-packed structure is_________.

(a)

1

(b)

2

(c)

3

(d)

4

Crystals of NaCI has yellow colour due the presence of_________.

(a)

cation vaccancy

(b)

F centres

(c)

both (a) and (b)

(d)

neither (a) nor (b)

The coordination number of ZnS is _______.

(a)

3

(b)

4

(c)

6

(d)

8

The correct order of packing efficiency in different types of unit cells is________.

(a)

fcc > bcc > sc

(b)

sc < fcc < bcc

(c)

fcc < bcc > sc

(d)

bcc < fcc < sc

Explain briefly seven types of unit cell.

What are point defects?

Which point effect in crystal doesn't alter the density of the relevant solid?

How many atoms can be present in a simple cubic lattice?

Experiment shows that Nickel oxide has the formula Ni_0.96.O_1.00. What fraction of Nickel exists as of Ni²⁺ and Ni³+ ions?

Why are solids rigid?

Silver crystallines in fcc lattice. If edge length of the cell is 4.07 x 10^-8 em and density is 10.5 g cm^-3. Calculate the atomic mass of silver

Distinguish the following.Crystal lattice and unit cell.

An atom crystallizes in fcc crystal lattice and has a density of 10 gcm⁻³ with unit cell edge length of 100pm. Calculate the number of atoms present in 1 g of crystal.

Ionic solids, which have anionic vacancies due to metal excess defect, develop colour. Explain with the help of a suitable example.

What are the general characteristics of solids?

Write note on impurity defect?