The packing efficiency of the face-centered cubic unit cell is:
(assuming that the atoms are touching each other)

1. 52.40 %

2. 68.04 %

3. 74 %

4. 79.06 %

Silver crystallizes in fcc lattice. If the edge length of the cell is 4.07 × 10⁻⁸ cm and density is 10.5 g cm⁻³, the atomic mass of silver is -

1. 120.31 g ${\mathrm{mol}}^{-1}$

2. 107.9 g ${\mathrm{mol}}^{-1}$

3. 207.60 g ${\mathrm{mol}}^{-1}$

4. 138.52 g ${\mathrm{mol}}^{-1}$

Copper crystallizes into an fcc lattice with an edge length of 3.61 × 10⁻⁸ cm. The density of copper crystal will be - 

1. 7.46 g cm^-3

2. 9.67 g cm^-3

3. 8.96 g cm^-3

4. 5.63 g cm^-3

An element with a molar mass of 2.7 × 10^-2 kg mol^-1  and density  2.7 × 10³ kg m^-3  forms a unit cell with an edge length of 405 pm. The type of unit cell is-

1. Simple cubic cell.

2. Face-centered cubic cell.

3. Body-centered cubic cell.

4. None of the above.

Niobium crystallizes in body-centred cubic structure. If the density is 8.55 g cm⁻³, the atomic radius of niobium (atomic mass 93 u) is -

1. 13.32 nm

2. 12.32 nm

3. 14.32 nm

4. 15.32 nm

The relation between the atomic mass of unknown metal with density and the dimension of its unit cell is given by  :

(Given: All the cell edge lengths are equal)

1. \(m \ = \ \frac{\rho a^{3}N_{A}}{Z} \)
2. \(m \ = \ \rho a^{3}N_{A}Z\)
3. \(m \ = \ \frac{Z}{\rho a^{3}N_{A}}\)
4. \(m \ = \ \frac{ZN_{A}}{a^{3}\rho}\)