Question

how many atom per unit cell z are present in bcc unit cell

Answer 1

Hey dude.....
Very gud mrng. ....

● The hexagonal closest packed (hcp) has a coordination number of 12 and contains 6 atoms per unit cell. The face-centered cubic (fcc) has a coordination number of 12 and contains 4 atoms per unit cell. The body-centered cubic (bcc) has a coordination number of 8 and contains 2 atoms per unit cell.

Hope this may help u.....

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Answer 2

Good Morning! :) 
Here, in bcc (body-centred cell)
we have 1 whole atom at the centre(please do take a look at the picture I uploaded for better concept) of the cubic cell.
Now at the lattice points or simply, corners of the cell, the atomic contribution,i.e,how much of an atom accommodate there is 1/8 of an atom (think of an ball being cut by three perpendicular planes like, so the no. of parts we got is 8)
So in total, at every corner of the cubic cell, we have 8 such 1/8th pieces,i.e, 8×1/8= 1 atom
therefore, total no. of atoms become= 1+1= 2

I just uploaded a pic for clearing your concept.
Hope I helped! ^^"
 Have a nice day ahead!