S C Kheterpal, S N Dhawan and, P N Kapil Solutions for Chapter: States of Matter: Solid State, Exercise 22: Competition Focus

In hexagonal close packing, the difference in the number of tetrahedral and octahedral voids per unit cell is

${\mathrm{NH}}_4^{+}$ and ${\mathrm{Br}}^{-}$ ions have ionic radii of $143 \mathrm{pm} \mathrm{and} 196 \mathrm{pm}$respectively. The coordination number of ${\mathrm{NH}}_4^{+}$ ion in ${\mathrm{NH}}_4\mathrm{Br}$ is

Iron ($\mathrm{II}$) oxide has a cubic structure and each unit cell has side $5 \mathrm{A}°$.If the density of the oxide is $4 \mathrm{g} {\mathrm{cm}}^{-3}$, the number of oxide ions present in each unit cell is (Molar mass of $\mathrm{FeO}=72 \mathrm{g} {\mathrm{mol}}^{-1}$ , ${\mathrm{N}}_{\mathrm{A}}= 6·02\times {10}^{23} {\mathrm{mol}}^{-1}$ )

${\mathrm{Al}}^{3+}$ ions replace ${\mathrm{Na}}^{+}$ ions at the edge centres of $\mathrm{NaCl}$ lattice. The number of vacancies in one mole $\mathrm{NaCl}$ is found to be $\mathrm{x} \times {10}^{23}$. The value of $\mathrm{x}$ approximately is

The oxide ${\mathrm{Tl}}_{\mathrm{n}}{\mathrm{Ca}}_2{\mathrm{Ba}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{10}$ is found to be superconductor at $125 \mathrm{K}$. The value of $\mathrm{n}$ is

The coordination number of $\mathrm{Al}$ in the crystalline state of ${\mathrm{AICI}}_3$ is

The number of hexagonal faces that are present in a truncated octahedron is

A crystalline solid of a pure substance has a face-centred cubic structure with a cell edge of $400 \mathrm{pm}$. If the density of the substance in the crystal is $8 \mathrm{g} {\mathrm{cm}}^{-3}$, then the number of atoms present in $256 \mathrm{g}$ of the crystal is $\mathrm{N}\times {10}^{24}$. The value of $\mathrm{N}$ is