I’m pretty sure the answer is D!
Answer: water should be recycled
Explanation:
Find moles of MgCl first by dividing by the molar mass.
21.9 g / 95.211 g/mol = 0.230 mol MgCl
Then divide by L of water to get the molarity.
0.230 mol / 0.750 L = 0.307 M MgCl