Frenkel and Schottky defects are

• nucleus defects

• non-crystal defects

• crystal defects

• nuclear defects

In the crystal of CsCl, the co-ordination number changes from 8:8 to 6:6 by:

• applying high pressure

• applying low temperature

• applying high temperature

• applying low pressure

A compound CuCl has face-centred cubic structure. Its density is 3.4 g cm^-3 , The length of unit cell is:

• 8.734 $\stackrel{0}{\mathrm{A}}$

• 5.834 $\stackrel{0}{\mathrm{A}}$

• 5.783 $\stackrel{0}{\mathrm{A}}$

• 8.153 $\stackrel{0}{\mathrm{A}}$

If the positions of Na⁺ and Cl^- are interchanged in NaCl , the crystal lattice with respect to Na⁺ and CI^- is:

• bcc and fcc

• fcc and bcc

• both fcc

• both bcc

45.

The crystal with metal deficiency defect is :

• NaCl

• FeO

• KCl

• ZnO

ZnO is white when cold and yellow when heated. It is due to the development of

• Frenkel defect

• metal excess defect

• Schottky defect

• metal deficiency defect.

Among the following, the compound that is both paramagnetic and coloured is

• K₂Cr₂O₇

• (NH₄)₂[TiCl₆]

• VOSO₄

• K₃[Cu(CN)₄]

If an atom crystallises in bee lattice with r= 4 Å then the edge length will be

• 2 Å

• 8 Å

• 2.39 Å

• 9.23 Å

A mineral having the formula AB₂ crystallizes in the cubic close-packed lattice , with the A atoms occupying the lattice points. The fraction of the tetrahedral sites occupied by B atoms is :

• 20 %

• 40 %

• 60 %

• 100 %

A forms hcp lattice and B are occupying 1/3^rd of tetrahedral voids, then the formula of compound is

• AB

• A₃B₂

• A₂B₃

• AB₄