To calculate the molarity of the NaCl solution, we need to determine the number of moles of NaCl in the solution, and then divide by the volume of the solution in liters.
The molar mass of NaCl is approximately 58.44 g/mol, so 263.7 g of NaCl is approximately 4.51 moles of NaCl.
The volume of the solution is given as 2.0 L.
Therefore, the molarity of the solution is:
Molarity = moles of solute / liters of solution
Molarity = 4.51 moles / 2.0 L
Molarity = 2.255 M
Therefore, the molarity of the NaCl solution is 2.255 M.