Question

Calculate the volume (mL) of 2.81 M magnesium phosphate solution require to prepare 43.20 mL of 2.1000 %w/v solution of Mg3(PO4)2 . [Answer in 3 decimal places].

Answer 1

I would convert 2.10% w/v Mg3(PO4)2 to molarity first.
2.10/molar mass Mg3(PO4)2 then
M Mg3(PO4)2 = moles/0.100L = ?

Then use the dilution formula of
mL1 x M1 = mL2 x M2
You may be familiar with
c1v1 = c2v2