Q. The pyknometric density of sodium chloride crystal is $2.165 \times 10^{3}\ kg\ m^{- 3}$, while its X-rays density is $2.178 \times 10^{3}\ kg\ m^{- 3}$. The fraction of unoccupied sites in sodium chloride crystal is
A) 5.96
B) 5.96 $\times 10^{- 1}$
C) 5.96 $\times 10^{- 2}$
D) 5.96$\times 10^{- 3}$
Explanation
(d)
Difference $= 2.178\ \times \ 10^{3} - \ 2.165 \times 10^{3} = 0.013 \times 10^{3}$
Fraction unoccupied $= \frac{0.013\ \times \ 10^{3}}{2.178\ \times \ 10^{3}} = 5.96 \times 10^{- 3}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.