Answer: The volume of water required is 398 mL
Step-by-step explanation:
To calculate the molarity of solution, we use the equation:

We are given:
Mass of solute (manganese (II) nitrate tetrahydrate) = 16 g
Molar mass of manganese (II) nitrate tetrahydrate = 251 g/mol
Molarity of solution = 0.16 M
Putting values in above equation, we get:

Hence, the volume of water required is 398 mL