Arrange the ions `Ca^(2+), Cl^(-) and S^(2-)` in the decreasing order of their ionic radius.

Explanation

To arrange the ions \( Ca^{2+}, Cl^{-}, \) and \( S^{2-} \) in decreasing order of their ionic radius, we can follow these steps:

### Step 1: Understand the Concept of Ionic Radius
The ionic radius is a measure of the size of an ion. It is influenced by the charge of the ion and the number of electrons. Generally, cations (positively charged ions) are smaller than their neutral atoms because they lose electrons, which decreases electron-electron repulsion and allows the remaining electrons to be pulled closer to the nucleus. Conversely, anions (negatively charged ions) are larger than their neutral atoms because they gain electrons, increasing electron-electron repulsion.

### Step 2: Analyze the Given Ions
- **Cation**: \( Ca^{2+} \) - This ion has a +2 charge, meaning it has lost two electrons compared to its neutral atom. This results in a smaller ionic radius.
- **Anion**: \( Cl^{-} \) - This ion has a -1 charge, meaning it has gained one electron compared to its neutral atom. This results in a larger ionic radius than its neutral atom.
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