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

Copper metal has a face-centered cubic structure with the unit cell length equal to 0.361 nm. Picturing copper ions in contact along the face diagonal. The apparent radius of a copper ion is-

(A) 0.128                                         

(B) 1.42

(C) 3.22                                           

(D) 4.22

Choose the correct matching sequence from the possibilities given

A compound alloy of gold and copper crystallizes in a cube lattice in which the gold atoms occupy the lattice points at the corners of a cube and the copper atoms occupy the centres of each of the cube faces. The formula of this compound is-

(1) AuCu                                                   

(2) $AuC{u}_2$

(3) $AuC{u}_3$                                                 

(4) None of these 

1. a, b                                         

2. b, c

3. a, b, c                                     

4. a, c

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

(1) Triangular system                             

(2) Tetragonal system

(3) Monoclinic system                             

(4) Octahedral

Bragg’s equation is-

(1) $n\lambda =2\theta \sin \theta$                               

(2) $n\lambda =2d\sin \theta$

(3) $2n\lambda =d\sin \theta$                               

(4) $\lambda =\left(2d/n\right)\sin \theta$

The n of a cubic unit cell is 4. The type of cell as-

(1) Body centred                               

(2) Face centred

(3) Primitive                                     

(4) None of these

Close packing is maximum in the crystal which is-

(1) Simple cube                               

(2) bcc

(3) fcc                                             

(4) None

In a face centred cubic arrangement of metallic atoms, what is the relative ratio of the sizes of tetrahedral and octahedral voids ?

(1) 0.543                                   

(2) 0.732

(3) 0.414                                   

(4) 0.637