Here's how to determine the moles of ions present in 12.87 g of sodium (Na):

1. Convert grams to moles:

* Molar mass of Na: 22.99 g/mol

* Moles of Na: (12.87 g Na) / (22.99 g/mol) = 0.560 mol Na

2. Consider the ionization of Na:

* Sodium (Na) is a Group 1 element, meaning it readily forms a +1 cation (Na+). This means one mole of Na will produce one mole of Na+ ions.

3. Result:

* Moles of Na+ ions: 0.560 mol

Therefore, there are 0.560 moles of Na+ ions present in 12.87 g of Na.