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 %

Subtopic:  Density & Packing Fraction |
85%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

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 ${\mathrm{mol}}^{-1}$

Subtopic:  Density & Packing Fraction |
81%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

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

Subtopic:  Density & Packing Fraction |
50%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

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.

Subtopic:  Density & Packing Fraction |
77%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

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

Subtopic:  Density & Packing Fraction |
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints
To view explanation, please take trial in the course.
NEET 2025 - Target Batch

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. $$m \ = \ \frac{ZN_{A}}{a^{3}\rho}$$

Subtopic:  Density & Packing Fraction |
84%
From NCERT
To view explanation, please take trial in the course.
NEET 2025 - Target Batch
Hints