The effective radius of an iron atom is `1.42 Å`. It has a rock-salt structure. Calculate its density (Fe = 56)

Explanation

To calculate the density of iron with a rock-salt structure given its effective radius and molar mass, we can follow these steps:

### Step-by-Step Solution:

1. **Identify Given Values:**
- Effective radius of iron atom, \( r = 1.42 \, \text{Å} \)
- Molar mass of iron, \( M = 56 \, \text{g/mol} \)
- Avogadro's number, \( N_A = 6.022 \times 10^{23} \, \text{mol}^{-1} \)
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