Q. Copper crystallises in fcc unit cell with cell edge length of $3.608 \times 10^{-8}$ cm. The density of copper is 8.92 g $cm^{-3}$. Calculate the atomic mass of copper.
A) 65 u
B) 63.1 u
C) 31.55 u
D) 60
Explanation
[Solution] $M = \frac{d \times a^3 \times N_A}{Z} = \frac{8.92 \times (3.608 \times 10^{-8})^3 \times 6.022 \times 10^{23}}{4} \approx 63.1$ u. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.