XII CHEMISTRY SOLID STATE

The number of atoms per unit cell in simple, fcc and bcc unit cells are

• 1, 4, 2

• 1, 2, 4

• 2, 1, 4

• 2, 4, 1

In 3D close packing the ABCABCABC.....pattern gives rise to which type of close packing?

• Hexagonal Close Packing (hcp)

• Cubic Close Packing (ccp)

• Face Centred Cubic Packing (fcc)

• Both ccp and fcc

The packing efficiency in simple, fcc, bcc unit cells will be respectively

• 74% 52.4% 68%

• 52.4% 68% 74%

• 68% 74% 52.4%

• 52.4% 74% 68%

The relationship between the atomic radius (r) and edge length (a) of a simple, fcc, bcc cubic unit cell will be respectively

• $\frac{a}{2}$ $\frac{\sqrt{2}a}{4}$ $\frac{\sqrt{3}a}{4}$

• $\frac{a}{2}$ $\frac{\sqrt{3}a}{4}$ $\frac{\sqrt{2}a}{4}$

• $\frac{\sqrt{2}a}{4}$ $\frac{\sqrt{3}a}{4}$ $\frac{a}{2}$

• $\frac{\sqrt{3}a}{4}$ $\frac{a}{2}$ $\frac{\sqrt{3}a}{4}$

The coordination number in simple, fcc, bcc close packing arrangement will be respectively

• 1, 4, 2

• 6, 12, 8

• 4, 6, 8

• none of the above

The total number of tetrahedral voids and octahedral voids in a given cubic unit cell with N number of atoms will be respectively

• 2N and N

• N and 2N

• 4N and N

• N and 4N

What type of material is this one?

• Crystal

• Amorphous

• Covalent Crystal

• Ionic Crystal

What is the coordination number in the FCC structure?

• 24

• 12

• 8

• 4

In METAL EXCESS DEFECTS the sites where an electron gets trapped in the anionic vacancy disturbing the ratio of cation to anion is known as

• E- CENTRE

• F- CENTRE

• G- CENTRE

• I- CENTRE

Which of the following is not a characteristic of a crystalline solid?

• Definite and characteristic heat of fusion.

• Long range order or perfect arrangement of constituent particles

• Isotropic in nature

• clean cleavage or smooth edges on cutting with a knife