Question

. Potassium crystallises in a body centred
cubic unit cell. the mass of one unit cell is
1) 1.29x10-23 gm
2) 1.295 x 10-22 gm
3) 6.2x10-23 gm
4) 1.29x10-24 gm​

Answer 1

Answer:

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 =139=139×6.022×1023×6.022×1023

So, no of unit cell in 1 g potassium =1.54×1022/2=0.77×1022