Total volume of atoms present in a face-centre cubic unit cell of a metal is (r is atomic radius)

• 20πr³/3

• 24πr³/3

• 12πr³/3

• 12πr³/3

An ionic compound has a unit cell consisting of A ions at the corners of a cube and B ions on the centres of the faces of the cube. The empirical formula for this compound would be

• A₂B

• AB

• AB₃

• AB₃

Lattice energy of an ionic compounds depends upon

• Charge on the ion only

• Size of the ion only

• Packing of ions only

• Packing of ions only

Based on lattice energy and other considerations which one of the following alkali metal chlorides is expected to have the highest melting point.

• LiCl

• NaCl

• KCl

• KCl

What type of crystal defect is indicated in the diagram below?

• Frenkel defect

• Frenkel and Schottky defects

• Interstitial defect

• Interstitial defect

Which type of ‘defect’ has the presence of cations in the interstitial sites?

• Metal deficiency defect

• Schottky defect

• Vacancy defect

• Frenkel defect

In a close-packed body-centred cubic lattice of potassium, the correct relation between the atomic radius (r) of potassium and the edge-length (a) of the cube is

• r = $\frac{\mathrm{a}}{\sqrt{2}}$

• r = $\frac{\mathrm{a}}{\sqrt{3}}$

• r = $\frac{\sqrt{3}}{2}\mathrm{a}$

• r = $\frac{\sqrt{3}}{4}\mathrm{a}$

Ionic solids with Schottky defect may contain in their structure

• cation vacancies only

• cation vacancies and interstitial cations

• equal number of cation and anion vacancies

• anion vacancies and interstitial anions

Suppose the mass of a single Ag-atom is m. Ag metal crystallises in fcc lattice with unit cell of length a. The density of Ag metal in terms of a and m is

• $\frac{4\mathrm{m}}{{\mathrm{a}}^3}$

• $\frac{2\mathrm{m}}{{\mathrm{a}}^3}$

• $\frac{\mathrm{m}}{{\mathrm{a}}^3}$

• $\frac{\mathrm{m}}{4{\mathrm{a}}^3}$

20.

The unit cell length of sodium chloride crystal is 564 pm. Its density would be

• 1.082 g cm^-3

• 2.165 g cm^-3

• 3.247 g cm^-3

• 4.330 g cm^-3