Which of the following arrangements correctly represents hexagonal and cubic close packed structure respectively?

• ABAB. .. and ACBACB ......

• ABCABC....... and ABAB

• Both have ABCABC.....arrangement

• Both have ABAB.... arrangement

KF has ccp structure. How many F^- ions and octahedral voids are there in this unit cell respectively?

• 4 and 4

• 4 and 8

• 8 and 4

• 6 and 6

The number of atoms contained in a fee unit cell of a monoatomic substance is

• 1

• 2

• 4

• 6

If a be the edge length of the unit cell and r be the radius of an atom then for fee arrangement, the correct relation is

• 4a = $\sqrt{3}$r

• 4r = $\sqrt{3}$a

• 4r = $\sqrt{2}$a

• 4r = $\frac{\mathrm{a}}{\sqrt{2}}$

A solid AB has the NaCl structure. If radius of cation A⁺ is 120 pm, the maximum possible value of the radius of the anion B^- is

• 240 pm

• 60 pm

• 49.6 pm

• 290 pm

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

• $\frac{16}{3} {\mathrm{\pi r}}^3$

• $\frac{20}{3}{\mathrm{\pi r}}^3$

• $\frac{24}{3}{\mathrm{\pi r}}^3$

• $\frac{12}{3}{\mathrm{\pi r}}^3$

37.

A metallic element has a cubic lattice with edge length of unit cell of 2Å and density is 2.5g cm^-1. The number of unit cells in 200g of metal are :

• 1$\times$ 10²⁴

• 1 $\times$ 10²⁰

• 1 $\times$ 10²⁵

• 1 $\times$ 10²²

In a face-centered cubic lattice, a unit cell is shared equally by how many unit cells?

• 8

• 4

• 2

• 6

Which of the following statement regarding defect is correct.

• Due to Schottky defect, the density of crystalline solid decreases.

• Due to Frenkel defect, the density of crystalline solid decreases.

• Due to Schottky defect, entropy of solid decreases.

• Due to Frenkel defect, entropy of solid decreases.

Certain crystals produce electric signals on application of perssure. This phenomenon is called :

• pyroelectricity

• ferroelectricity

• piezoelectricity

• ferrielectricity