both b and d are correct however the ion reacts more readily to a number of different elements. not just Cl2 so the best correct answer is b: the positive charge on the nucleus of the ion us two units greater than the nuclear charge on the atom.
The main difference between a magnesium atom and a magnesium ion (\text{Mg}^{2+}) lies in their electronic configuration and stability. The magnesium ion is more stable due to having a full outer electron shell after losing two electrons. Therefore, the correct answer is A: The ion has a more stable electronic arrangement than the atom.
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