Correct Answer:- Option-C
Question15:-Packing efficiency of ccp structure is

A:-52.4%

B:-68%

C:-72%

D:-74%

Correct Answer:- Option-D

Question16:-Solid 'P' is insulator in solid state but conductor in molten state and in
aqueous solutions. What type of solid is it?

A:-Molecular

B:-Metallic

C:-lonic

D:-Covalent

Correct Answer:- Option-C

Question17:-Cobalt crystallises in hexagonal close packed structure. Its atomic
radius is 200 pm. The length of side (a) of unit cell is (Given 132-1414)

A:-566 pm
B:-438 pm
C:-687 pm
D:-369 pm
Correct Answer:- Option-A

Question18:-A compound forms cubic close packed structure. What is the total
number of voids in 1 mole of it?

^: -6.022 24102

مركا 9.033-:8

C:-18.066 x02

D:-12.044 x 10%

Correct Answer:- Option-C

Question19:-Copper crystallises such that the lattice get ABC ABC arrangement of
layers. This type of three dimensional packing is called

A:-Cubic close packing
B:-Body centred cubic packing
C:-Hexagonal close packing
D:-Primitive cubic packing
Correct Answer:- Option-A

Question20:-Which of the following statements are incorrect about crystalline solid?
(i) Melt at a sharp and characteristic temperature
(11) Definite and characteristic heat of fusion