The radius of a calcium ion is 94 pm and of an oxide ion is 146 pm. Predict the crystal structure of calcium oxide.

Explanation

To predict the crystal structure of calcium oxide (CaO), we will use the radius ratio rule. Here’s a step-by-step solution:

### Step 1: Identify the ionic radii
- The radius of the calcium ion (Ca²⁺) is given as 94 pm (picometers).
- The radius of the oxide ion (O²⁻) is given as 146 pm.

### Step 2: Calculate the radius ratio
- The radius ratio (r) is calculated using the formula:
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