Answer:
The concentration of a solution is usually calculated as the amount of solute (in this case, NaCl) divided by the volume of the solution. Given that you dissolved 200 g of NaCl in 2 L of water and obtained 2.5 L of solution, you can calculate the concentration as follows:
Concentration (g/L) = Amount of Solute (g) / Volume of Solution (L)
Concentration (g/L) = 200 g / 2.5 L
Concentration (g/L) = 80 g/L
Therefore, the ordinary concentration of this solution is 80 grams per liter.