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%

Gold (Au) crystallizes in cubic close packed (FCC). The atomic radius of gold is 144 pm and the atomic mass of Au=197.0 amu. The density of Au is

1. 19.4 g cm^-3 

2. 194 g cm^-3 

3. 39.4 g cm^-3 

4. 0.194 g cm^-3 

An alloy of copper, silver and gold is found to have copper constituting the ccp lattice. If silver atoms occupy the edge centres and gold is present at body centre, will have the formula

1. Cu₄AgAu

2. Cu Ag Au

3. Cu₄Ag₂Au

4. Cu₄Ag₃Au

At room temperature, sodium crystallizes in a BCC lattice with the cell edge (a) 4.24 Å. Find the density of sodium. (Atomic wt of Na=23)

1. 2.01 g/cm³ 

2. 1.002 g/cm³ 

3. 3.003 g/cm³ 

4. 2.004 g/cm³