[SPASH]

Which of the following compounds would result in an exchange reaction if mixed in an aqueous solution with Li3PO4?

1) NH4NO3
2) KClO3
3) CuSO4
4) Cs2O

I believe that to solve this problem, I have to figure out which combination will produce an insoluable product?  Correct?  If this is true, I think the correct answer is CuSO4, but is this insoluable?  
Is my line of thinking on this problem correct?

[Borek]

I believe that to solve this problem, I have to figure out which combination will produce an insoluable product?  Correct?  If this is true, I think the correct answer is CuSO4, but is this insoluable?  
Is my line of thinking on this problem correct?

Seems OK. Google for solubility rules - they are often a part of on-line chemistry courses (although it is much safer to use solubility products).