1 Calcium solution

2 Barium solution
3 Strontium solution
In which solution or solutions does not precipitate form when potassium ferro cyanide solution is added to the above solutions buffered with ammonia and ammonium chloride?

The best information I can find says that Ca is the only ion of the three that will ppt from NH3/NH4Cl buffered solution. The other two will not. I don't know from first hand experience.