A X⁺ Y^- has the Y^- ions arranged as below. If the X⁺ ions occupy half of the tetrahedral sites in the structure. The formula of solid is

1. XY

2. X₃Y₄

3. XY₂

4. X₂Y

NaCl is doped with $2\times {10}^{-3} \mathrm{mol}\%{\mathrm{SrCl}}_2$, the concentration of cation vacancies is

1. $12.04\times {10}^{18} {\mathrm{mol}}^{-1}$

2. $10.01\times {10}^{18} {\mathrm{mol}}^{-1}$

3. $12.04\times {10}^{20} {\mathrm{mol}}^{-1}$

4. $4.02\times {10}^{18}{\mathrm{mol}}^{-1}$

A solid XY has NaCl structure. If radius of X⁺ is 100 pm, the radius of Y^- ion is

1. 136.6 to 241.6 pm

2. 341.6 to 134.6 pm

3. 128 pm

4. 136.8 pm

The ionic radii of Rb⁺ and I^- are 1.46 Å and 2.16 Å respecitvely. The most probable type of structure exhibited by it is

1. CaF₂ type

2. ZnS type

3. CsCl type

4. NaCl type

A solid has 3 types of atoms namely X, Y and Z. X forms an FCC lattice with Y atoms occupying all the tetrahedral voids and Z atoms occupying half the octahedral voids. The formula of the solid is

1. XYZ

2. X₂Y₄Z

3. X₄YZ₂

4. X₄Y₂Z

Calculate the $\mathrm{\lambda }$ of X-rays which give a diffraction angle 2$2\mathrm{\theta }=16.80°$ for a crystal. (Given interplanar distance=0.200 nm; diffraction=first order; sin $8.40°$=0.1461)

1. 58.4 pm

2. 5.84 pm

3. 584 pm

4. 648 pm

In a compound XY, the ionic radii X⁺ and Y^- are 88 pm and 200 pm respectively. What is the coordination number of X⁺?

1. 4

2. 6

3. 8

4. 10

The edge length of unit cell of a metal having molecular weight 75 g/mol is 5 Å which crystallizes in cubic lattice. If the density is 2 g/cc then find the radius of metal atom. $(\mathrm{NA}=6\times {10}^{23})$. Give the answer in pm.

1. 116.5 pm

2. 316.5 pm

3. 216.5 pm

4. 416.5 pm

Sodium metal crystallizes as a body-centred cubic lattice with the cell edge 4.29 Å. What is the radius of sodium atom?

1. $2.371\times {10}^{-7} \mathrm{cm}$

2. $1.857\times {10}^{-8} \mathrm{cm}$

3. $3.817\times {10}^{-8} \mathrm{cm}$

4. $7.312\times {10}^{-7} \mathrm{cm}$

A metallic element crystallizes into a lattice containing a sequence of layers ABABAB... Any packing of spheres leaves out voids in the lattice. What percentage by volume of this lattice is empty space?

1. 26%

2. 74%

3. 50%

4. 85%