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

If the radius of the octahedral void is r and the radius of the atoms in close packing is R, the relation between r and R would be -

1. r = 0.114R

2. r = 0.444R

3. r = 1.414R

4. r = 0.414R

Higher conductivity of p-type and n-type semiconductors is due to:

(i) Ge is doped with In

(ii) Si is doped with B. 

The semiconductors formed in the above cases are :

1. (i) n-type semiconductor  (ii) p-type semiconductor .

2. (i) p-type semiconductor  (ii) n-type semiconductor .

3. p-type semiconductor in both the cases.

4. n-type semiconductor in both the cases.

Aluminum crystallizes in a cubic close-packed structure. It's metallic radius is 125 pm. The number of unit cells in 1.00 cm³ of aluminum are : 

1. 2.27 x 10²²

2. 354 x 10²²

3. 4.54 x 10²²

4. 127 x 10²⁰

NaCl is doped with 10⁻³ mol % of SrCl₂. The number of cation vacancies post doping would be -

1. 4.022 × 10⁸

2. 5.022 × 10¹⁸

3. 6.022 × 10¹⁸

4. 7.022 × 10⁸

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

The correct statement among the following is -

A defect that has an equal number of missing cations and anions is:

1. Schottky defect.

2. Frenkel defect.

3. Both (1) and (2)

4. None of the above.

The magnetic substances that have lesser magnetic moment than expected is known as -

1. Paramagnetic.

2. Ferrimagnetic.

3. Antiferromagnetic.

4. None of the above.