Which arrangement of electrons leads to anti-ferromagnetism?

1.  

2.  

3. Both (1) and (2)

4. None of the above.

The intermetallic compound LiAg has a cubic crystalline structure in which each Li atom has 8 nearest neighbour silver atoms and vice-versa. What is the type of unit cell?

1. Body centred cubic

2. Face centred cubic

3. Simple cubic for either Li atoms alone or Ag atoms alone

4. None of the above

The arrangement ABC ABC.. is referred to as.

1. octahedral close packing

2. hexagonal clase packing

3. tetrahedral close packing

4. cubic close packing

How many unit cells are present in a cube shaped ideal crystal of NaCl of mass 1.00g?

[ Atomic masses Na=23, Cl = 35.5]

1. 2.57 x 10²¹

2. 5.14 x 10²¹

3. 1.28 x 10²¹

4. 1.71 x 10²¹

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

1. 0.714

2. 0.225

3. 0.02

4. 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

In a compound, atoms of element Y form ccp lattice, and those of element X occupy 2/3^rd of tetrahedral voids. The formula of the compound will be :-
1. X₃Y₄
2. X₄Y₃ 
3. X₂Y₃
4. X₂Y

A spinel is an important class of oxides consisting of two types of metal ions with the oxide ions arranged in ccp layers. The normal spinel has 1/8^th of the tetrahedral void occupied  by one type of metal and one half of the octahedral voids occupied by another type of metal ions. Such a spinel is formed by Zn²⁺, Al³⁺ and O^2- with Zn²⁺ in tetrahedral void. Give the simplest formula of the spinel.

1. ZnAl₂O₄

2. ZnAl₂O₃

3. ZnAlO

4. None of these

Close packing is maximum in the crystal lattice of:

1. simple cubic

2. face centred

3. body centred

4. none of these

Frenkel defect is noticed in:

1. AgBr

2. ZnS

3. Agl

4. All of the above