Lithium metal crystallizes in a body-centered cubic crystal. If the length of the side of the unit cell of lithium is 351 pm, the atomic radius of the lithium will be:

1. 240.8 pm

2. 151.8 pm

3. 75.5 pm

4. 300.5 pm

If 'a’ stands for the edge length of the cubic systems: simple cubic, body-centered cubic, and face-centered cubic, then the ratio of radii of the spheres in these systems will be respectively: 

1. $\frac{1}{2}\mathrm{a\; :}$ $\frac{\sqrt{3}}{4}\mathrm{a}$ $:$ $\frac{1}{{\displaystyle 2}\sqrt{2}}\mathrm{a}$

2. $\frac{1}{2}\mathrm{a\; :}$ $\sqrt{3}\mathrm{a}$ $:$ $\frac{1}{\sqrt{2}}\mathrm{a}$

3. $\frac{1}{2}\mathrm{a\; :}$ $\frac{\sqrt{3}}{2}\mathrm{a}$ $:$ $\frac{\sqrt{2}}{{\displaystyle 2}}\mathrm{a}$

4. $1\mathrm{a\; :}$ $\sqrt{3}\mathrm{a}$ $:$ $\sqrt{2}\mathrm{a}$

Silicon gives p-type of semiconductor on doping with:

1. Germanium.

2. Arsenic.

3. Selenium.

4. Boron.

The fraction of total volume occupied by the atoms present in a simple cube is:

1. $\frac{\mathrm{\pi }}{6}$

2. $\frac{\mathrm{\pi }}{3\sqrt{2}}$

3. $\frac{\mathrm{\pi }}{4\sqrt{2}}$

4. $\frac{\mathrm{\pi }}{4}$

CsBr crystallises in a body-centered cubic lattice. The unit cell length is 436.6 pm. Given that the atomic mass of Cs = 133 amu and that of Br = 80 amu and the Avogadro number being 6.02×10²³ mol^-1, the density of CsBr is:

1. 42.5 $g/c{m}^3$

2. 0.425 $g/c{m}^3$

3. 8.25 $g/c{m}^3$

4. 4.25 $g/c{m}^3$

The appearance of colour in solid alkali metal halides is generally due to:

1. F-centres.

2. Schottky defect.

3. Frenkel defect.

4. Interstitial positions.

A compound is formed by cation C and anion A. The anions form hexagonal close packed (hcp) lattice and the cations occupy 75 % of octahedral voids. The formula of the compound is:

1. ${\mathrm{C}}_3{\mathrm{A}}_4$

2. ${\mathrm{C}}_2{\mathrm{A}}_3$

3. ${\mathrm{C}}_3{\mathrm{A}}_2$

4. ${\mathrm{C}}_4{\mathrm{A}}_3$

If the lattice parameter for a crystalline structure is 3.6 Å, then the atomic radius in fcc crystal is: 

1. 1.81 Å

2. 2.10 Å

3. 2.92 Å

4. 1.27 Å

Copper crystallizes in a face-centered cubic lattice with a unit cell length of 361 pm. The radius of the copper atom is:

1. 128 pm

2. 157 pm

3. 181 pm

4. 108 pm