Question

Question 11-12 is based on the following given information:
Assume a hypothetical cubic crystal lattice, named JEE-centered cubic (jcc) with the following characteristics:
I. An atom is present at all the corners of the cube
II. An atom is present at the center of two pairs of opposite faces
III. An atom is present at the center of all the edges of the cube
IV. One atom is present at its body-center
How many atoms are effectively present per unit cell in this hypothetical crystal lattice?

• A. 8
• B. 7
• C. 6
• D. 5

Answer 1

The correct option is B 7

I. 8 corner atom $\times \left(\frac{1}{8}\right)$ atom per unit cell = 1 atom

II. 4 face-centered atoms $\times \left(\frac{1}{2}\right)$ atom per unit cell = 2 atom

III. 12 edge-centered atoms $\times \left(\frac{1}{4}\right)$ atom per unit cell = 3 atom

IV. 1 body centered atom $\times$ 1 atom per unit cell = 1 atom

So, Total number of atoms per unit cell $=1+2+3+1=7$ atoms