Chemistry , i'm calculate the molarity of a saline solution prepared by dissolving 19.3 g of sodium chloride in 250 ml of water. show all !

First, let's calculate the concentration by gram per liter:
C =  = 77.2 g/L

Now, let's convert it to molarity, knowing that the molar mass of sodium chloride is 58.5g/mol:
Molarity =  = 1.31 M

For more explanation:
molarity =  *  = 

The answer to that would be magnesium