The empty space in hcp is ______ and that in bcc paking is _______.

Explanation

To solve the question regarding the empty space in hexagonal close packing (hcp) and body-centered cubic (bcc) packing, we will follow these steps:

### Step 1: Understanding Hexagonal Close Packing (hcp)
1. In hcp, the effective number of atoms (Z) in a unit cell is 6.
2. The volume occupied by these atoms can be calculated using the formula:
\[ \text{Volume Occupied} = Z \times \left(\frac{4}{3} \pi r^3\right) = 6 \times \left(\frac{4}{3} \pi r^3\right) \]
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