Explanation:
It is known that molarity is the number of moles present in a liter of solution.
Molarity = [tex]\frac{\text{no. of moles}}{volume}[/tex]
Also, number of moles equal mass divided by molar mass. And, molar mass of calcium is 40.07 g/mol.
No. of moles = [tex]\frac{mass}{\text{molar mass}}[/tex]
= [tex]\frac{1.0 g}{40.07 g/mol}[/tex]
= 0.025 mol
Therefore, calculate the molarity as follows.
Molarity = [tex]\frac{\text{no. of moles}}{volume}[/tex]
= [tex]\frac{0.025 mol}{1.0 L}[/tex]
= 0.025 M
Thus, we can conclude that molarity of [tex]Ca^{2+}[/tex] in milk is 0.025 M.