Answer :
To make a 2.75 m solution with a final volume of 350.0 ml using a concentrated solution that's 9.00 m, you would need 107 ml of the concentrated magnesium chloride solution. Therefore, the correct option is c.
To calculate the volume of concentrated magnesium chloride needed to make a 2.75 m solution at a total volume of 350.0 ml, you can use the concept of dilution, where M1V1 = M2V2 (where M is molarity and V is volume). In this equation, M1 is the initial molarity (9.00 m), M2 is the final molarity (2.75 m), V2 is the final volume (350.0 ml), and V1 is the initial volume we want to find.
As per the equation:
M1V1 = M2V2
Rearranging for V1 gives us:
V1 = M2V2 / M1
Substitute the known values:
V1 = (2.75 m * 350.0 ml) / 9.00 m
V1 = 962.5 m*ml / 9 m = 107 ml
Therefore, 107 ml of the concentrated solution is needed.
