Examine the given defective crystal:
 

Answer the following questions:

(i) What type of stoichiometric defect is shown by the crystal?

(ii) How is the density of the crystal affected by this defect?

 (iii) What type of ionic substances shows such defect? 

How many atoms constitute one unit cell of a face-centered cubic crystal? 

(a) What type of semiconductor is obtained when silicon is doped with boron?

(b) What type of magnetism is shown in the following alignment of magnetic moments?

(c) What type of point defect is produced when AgCl is doped with CdCl₂?

What is meant by ‘doping’ in a semiconductor?

Tungsten crystallizes in the body-centred cubic unit cell. If the edge of the unit cell is 316.5 pm, what is the radius of tungsten atom?

Iron has a body centred cubic unit cell with a cell dimension of 286.65 pm. The density of iron is 7.874 g cm^-3. Use this information to calculate Avogadro's number (At. Mass of Fe = 55.845 u)

‘Crystalline solids are anisotropic in nature’. What does this statement mean?

258.

Silver crystallizes in face-center cubic unit cell. Each side of this unit cell has a length of 400 pm. Calculate the radius of the silver atom. (Assume the atoms just touch each other on the diagonal across the face of the unit cell. That is each face atom is touching the four corner atoms.) 

Define the following terms:

(i) Primitive unit cells

(ii) Schottky defect

(iii) Ferromagnetism

(a) Why does the presence of an excess of lithium make LiCl crystals pink?

(b) A solid with cubic crystal is made of two elements P and Q. Atoms of Q are at the corners of the cube and P at the body-center. What is the formula of the compound?