Arrange the following ions in order of decreasing ionic radii :` Li^(2+) , He ^(+) , Be^(3+)`

Explanation

To arrange the ions \( \text{Li}^{2+} \), \( \text{He}^{+} \), and \( \text{Be}^{3+} \) in order of decreasing ionic radii, we can follow these steps:

### Step 1: Identify the number of electrons in each ion.
- **Lithium ion (\( \text{Li}^{2+} \))**: Lithium has 3 electrons, and losing 2 gives us 1 electron.
- **Helium ion (\( \text{He}^{+} \))**: Helium has 2 electrons, and losing 1 gives us 1 electron.
- **Beryllium ion (\( \text{Be}^{3+} \))**: Beryllium has 4 electrons, and losing 3 gives us 1 electron.

### Step 2: Determine if the ions are isoelectronic.
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