Q. The orthorhombic, the value of $a,\ b$and $c$are respectively $4.2\ \mathring{\mathrm{A}},\ \ 6.8A\ \mathring{\mathrm{A}}$ and $8.3\ \mathring{\mathrm{A}}.\$Given the molecular mass of the solute is 155 g $mol^{- 1}$ and that of density is 3.3g/cc, the number of formula units per unit cell is
A) 2
B) 3
C) 4
D) 6
Explanation
(c)
$Z = \frac{V \times N \times d}{m}$
$\ \ \ \ = \frac{4.2 \times 8.6 \times 8.3 \times 10^{- 21} \times 6.023 \times 10^{23} \times 3.3}{155}$
$\ \ \ \ = 3.14$
$\ \ \ \ \approx 4$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.