Here's how to calculate the concentration of the sodium hydroxide solution:

1. Convert grams of NaOH to moles:

* Molar mass of NaOH: 22.99 g/mol (Na) + 16.00 g/mol (O) + 1.01 g/mol (H) = 40.00 g/mol

* Moles of NaOH: (40.0 g NaOH) / (40.00 g/mol NaOH) = 1.00 mol NaOH

2. Calculate the molarity (concentration):

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

* Molarity = (1.00 mol NaOH) / (0.50 L solution) = 2.0 M

Therefore, the concentration of the sodium hydroxide solution is 2.0 M (2.0 molar).