Q. X- ray analysis shows that the unit cell length in $NaCl$ is 562.8 pm. Calculate the density you would expect on this basis, $N_{A} = 6.023\ x10^{23}{mol}^{- 1}$
A) 0.3216 g $cm^{- 3}$
B) 2.179 g $cm^{- 3}$
C) 1.859 g $cm^{- 3}$
D) 2.346 g $cm^{- 3}$
Explanation
(b)
Destiny, $d = \frac{Z\ M}{a^{3}N_{A}}$
$= \frac{4(58.5)g\ mol^{- 1}}{\left( 5.628 \times 10^{- 8}cm \right)^{3}(6.023 \times 10^{23}{mol}^{- 1})}$
$= 2.179\ g\ cm^{- 3}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.