Mg in solid-state shows electronic conductivity due to the presence of-

1. Free electrons.

2. Positive holes.

3. No electrons.

4. None of the above

MgCl₂ in the molten state is-

1. p-type semiconductor

2. n-type semiconductor

3. Electrolytic conductors

4. Electronic conductors

Cubic close packing in three dimensions is

 1. Triangular voids

2. Pattern of spheres is repeated in every fourth layer

3. Coordination number =4

4. Pattern of sphere is repeated in alternate layers

Number of octahedral voids are present per unit cell in a cubic close packed structure :

1. 4

2. 8

3. 6

4. 2

Number of  tetrahedral voids voids are present per unit cell in a cubic close packed structure : 

1. 4

2. 8

3. 6

4. 2

Doping affects the property of semiconductors. It -

1. Increases the conductivity of semiconductors.

2. Decreases the conductivity of semiconductors.

3. No effect on conductivity of semiconductors.

4. None of the above.

Non-stoichiometric defect present in the sample of ferrous oxide with formula Fe_0.93O_1.00  - 

1. Metal deficiency defect

2. Metal excess defect 

3. Frenkel defect

4. Schottky defect

Select the correct option based on statements below:

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 ${\mathrm{mol}}^{-1}$