How many mL of 0.0500 M EDTA are required to react with 54.0 mL of 0.0190 M Ca2+?

Answer 1

EDTA reacts with metals 1:1.
mols Ca^2+ = M x L = ?
mols EDTA = mols Ca^2+
Then M EDTA = mols EDTA/L EDTA. You know M and mols, solve for L and convert to mL.