Looking for classes? Ksquare Career Institute, Bengaluru →
The Solid State
Imperfections in Solids: Schottky Defect
1 question from 1 paper, each with its answer.
- question
- 1
- paper
- 1
- of The Solid State
- 2.22%
Concepts tested
- Fraction of vacant sites from densities
All Questions
2003 AIPMT 1 question
-
The pyknometric density of sodium chloride crystal is $2.165 \times 10^3$ kg m$^{-3}$ while its X-ray density is $2.178 \times 10^3$ kg m$^{-3}$. The fraction of unoccupied sites in sodium chloride crystal is :The X-ray density is calculated from the unit cell dimensions assuming every lattice site is occupied. The pyknometric (measured) density is slightly lower because some sites are vacant (Schottky defects).
Fraction of unoccupied sites $= \dfrac{\text{X-ray density} - \text{pyknometric density}}{\text{X-ray density}}$
$= \dfrac{2.178 \times 10^3 - 2.165 \times 10^3}{2.178 \times 10^3} = \dfrac{0.013}{2.178}$
$= 5.96 \times 10^{-3}$
So the fraction of unoccupied sites is $5.96 \times 10^{-3}$.