Which ions remain in solution, unreacted, after each of the following pairs of solutions is mixed (which ions are spectator)?

Which ions remain in solution, unreacted, after each of the following pairs of solutions is mixed (which ions are spectator)? Write the complete molecular equation, the total ionic equation and the NET ionic equation.

a) potassium carbonate and magnesium sulfate

b)lead nitrate and lithium sulfide

c)ammonium phosphate and calcium chloride