The empty space left in a hexagonal close packing of spheres in three dimensions is

1. 64%

2. 26%

3. 14%

4. 52.4%

The void formed by closed packed array of spheres located at the alternate corners of each face is

1. octahedral void

2. tetrahedral void

3. triangular void

4. both 1 and 2

A drop of liquid acquires a spherical shape because of

1. its tendency to maximize its surface area

2. its tendency to acquire minimum surface area

3. its viscous nature

4. none of these

Liquefied metals contain

1. metal anions only

2. metal cations only

3. metal kernels and mobile electrons

4. metal atoms only

Which of the following is the correct relation between enthalpy of vaporization (Joule/mole) and boiling point of a liquid?

1. $∆\mathrm{H}=1.5 {\mathrm{P}}_{\mathrm{b}}$

2. $∆\mathrm{H}=77 {\mathrm{T}}_{\mathrm{b}}$

3. $∆\mathrm{H}=88 {\mathrm{T}}_{\mathrm{b}}$

4. $∆\mathrm{H}=0.5 {\mathrm{T}}_{\mathrm{b}}$

In which of the following pairs the cations occupy same type of site

1. Zinc blende, Na₂O

2. NaCl, CsCl

3. Na₂O, CaF₂ 

4. CsBr, ZnS

The structure of TlCl is similar to CsCl. What should be the radius ratio in TlCl?

1. 0.225-0.414

2. 0.155-0.225

3. 0.732-1.000

4. 0.414-0.732

If molar mass of AB is 95 g mol^-1 and a is edge length, then the density of crystal structure is

1. $\frac{4\times 95}{{\mathrm{a}}^3\times {\mathrm{N}}_{\mathrm{A}}}$

2. $\frac{4{\mathrm{N}}_{\mathrm{A}}}{{\mathrm{a}}^3\times 95}$

3. $\frac{2\times 95}{{\mathrm{a}}^3\times {\mathrm{N}}_{\mathrm{A}}}$

4. $\frac{2{\mathrm{N}}_{\mathrm{A}}}{{\mathrm{a}}^3\times 95}$

The radius ratio (r⁺/r^-) of KF is 0.98. The structure of KF is similar to

1. NaCl

2. CsCl

3. ZnS

4. Both 1 and 2

Na₂O has antifluorite structure. In Na₂O, the coordination number of ${\mathrm{N}}^{{\mathrm{a}}^{+}}$ and ${\mathrm{O}}^{2^{-}}$ are respectively

1. 4,4

2. 6,6

3. 4,8

4. 8,8