The pair having only molecular solids among the following is -

1. Brass and SiC

2. Ammonium phosphate (NH₄)₃PO₄

3. SiC and plastic 

4. Tetra phosphorus decaoxide (P₄O₁₀) and I₂

In a cubic close-packed structure, the coordination number of atoms is -

1. 12

2. 8

3. 1

4. 4

The number of lattice points in one unit cell of face-centred tetragonal lattice is  -

1. 4 

2. 12

3. 14 

4. 9

The similarity between metallic and ionic crystals is -

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