Question

Potassium crystallises in BCC unit cell . Mass of 1 unit cell is

Answer 1

In BCC unit cell, there are eight atoms at comes and one atom at body center.
So, total number of atoms per unit cell =18=18×8+1=2×8+1=2
Now, no of atoms 1 gm potassium =1/39=1/39×6.022×10^23×6.0^22×10^23
So, no of unit cell in 1 g potassium =1.54×10^22/2=0.77×10^22