Which is covalent solid?

(1) Fe₂O₃

(2) Diamond

(3) Graphite 

(4) All of these

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

(1) CA

(2) A₂

(3) C₂A₃

(4) C₃A₂

Graphite in an example of-

(1) Ionic solid

(2) Covalent solid

(3) Vander waal's crystal

(4) Metallic crystal

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,

(A) a,b

(B) b,c

(C) a,b,c

(D) a,c

Which arrangement of electrons leads to anti-ferromagnetism?
(1)  ↑↑↑↑
(2)  ↑↓↑↓
(3) Both (a) and (b)
(4) None of these

Among the following types of voids. which one is the largest void:-

(A) Triangular system
(B) Tetragonal system
(C) Monoclinic system
(D) Octahedral

The ratio of cations to anion in a closed pack tetrahedral is:

(a) 0.714
(b) 0.225
(c) 0.02
(d) none of these

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

Frenkel defect is noticed in:

(a) AgBr

(b) ZnS

(c) Agl

(d) all of these

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