The similarity between metallic and ionic crystals is -

1.	Both these crystal types are held by the electrostatic force of attraction.
2.	Both these crystal types are held by the Van der Waal's forces of attraction.
3.	Both these crystal types are held by  hydrogen bonding.
4.	Both these crystal types are held by covalent bonding.

A cubic solid is made of two elements P and Q. Atoms of Q occupy the corners of the cube and P occupy the body centre. The formula of this compound and the coordination number of Q are respectively - 

1. PQ, 8

2. P₂Q, 8

3. P₂Q₂, 8

4. PQ, 12

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 -