Chemistry Question... I don't know how to do this problem...?

Question

In a .400 M Ca3(PO4)2 solution, what is the molarity of calcium ions in the solution?

A) 0.400 M Ca+2

B) 0.800 M Ca+2

C) 1.20 M Ca+2

D) 1.60 M Ca+2

E) 2.00 M Ca+2

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I don't really know how to work this problem...

the furthest I got was that 38.7% was the percent composition of calcium...

i don't really know what to do with that...

a little help?

Answer 1

Each mole of calcium(III) diphosphate contains 3 calcium ions so the molarity of calcium ions = 0.400 x 3 = 1.20M