Identify the best choice in the list:
(i) Largest ionic size `:Mg^(2+), Ca ^(2+), Ba ^(2+)`
(ii) Smallest size `:I ^(+), I^(-), I`
(iii) Highest negative electron gain enthalpy: `Br, Cl,F`

Explanation

To solve the question, we will analyze each part step by step.

### Part (i): Largest Ionic Size - `Mg^(2+), Ca^(2+), Ba^(2+)`

1. **Identify the Elements**: The ions given are magnesium (Mg²⁺), calcium (Ca²⁺), and barium (Ba²⁺). All these elements belong to Group 2 of the periodic table.

2. **Understand Ionic Size Trend**: As we move down a group in the periodic table, the ionic size increases. This is due to the addition of electron shells, which increases the distance between the nucleus and the outermost electrons.

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