Here's how to calculate the moles of sodium chloride (NaCl) in the solution:

1. Convert mL to Liters:

* 250 mL * (1 L / 1000 mL) = 0.250 L

2. Use the Molarity Formula:

* Molarity (M) = moles of solute / liters of solution

* We know the molarity (1.20 M) and the volume (0.250 L). We can rearrange the formula to solve for moles:

* moles of solute = Molarity * liters of solution

3. Calculate the moles of NaCl:

* moles of NaCl = 1.20 M * 0.250 L = 0.300 moles

Therefore, there are 0.300 moles of sodium chloride in 250 mL of a 1.20 M solution.