Graphite and diamond are ________.

(a)

Covalent and molecular crystals

(b)

ionic and covalent crystals

(c)

both covalent crystals

(d)

both molecular crystals

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_x, B_y is ________.

(a)

AB

(b)

AB₃

(c)

A₃B

(d)

A₈B₆

The number of unit cells in 8 gm of an element X (atomic mass 40) which crystallizes in bcc pattern is (N_A is the Avogadro number)________.

(a)

6.023 x 10²³

(b)

6.023 x 10²²

(c)

60.23 x 10²³

(d)

\(\left( \frac { 6.023\times { 10 }^{ 23 } }{ 8\times 40 } \right) \)

Which of the following is characteristic of ionic solids?

(a)

Very low value of electrical conductivity in the molten state

(b)

Brittle nature

(c)

Very strong forces of attractions

(d)

Anisotropic nature

An example of metal deficiency defect _______.

(a)

NaCl

(b)

AgCl

(c)

CsCl

(d)

FeS

Metal deficiency defect

(1)

AgBr

Metal excess defect

(2)

FeO

Metal deficiency defect

(3)

NaCI

Schottky defect

(4)

KCI

Frenkel defect

(5)

FeO with Fe³⁺