Iron occurs as BCC as well as FCC unit cell. If the effective radius of an atom of iron is 124 pm, compute the density of iron in both these structures.

Explanation

To compute the density of iron in both BCC (Body-Centered Cubic) and FCC (Face-Centered Cubic) structures, we will follow these steps:

### Step 1: Understand the structure and the number of atoms per unit cell

**BCC Structure:**
- In a BCC unit cell, there are 8 corner atoms and 1 atom at the body center.
- The contribution of each corner atom is \( \frac{1}{8} \), so the total contribution from the corners is \( 8 \times \frac{1}{8} = 1 \).
- Adding the body-centered atom gives a total of \( 1 + 1 = 2 \) atoms per unit cell.
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