compunds react with eachother to form precipitate--just see if i am doing it right?

Question

the question::
Which of the following compounds will react with eachother to form of a precipitate(determine all possible combinations)-Calcium carbonate, aluminum sulfate, barium nitrate, ammonium hydroxide, magnesium acetate

my answers::
CaCO3(aq) + 2NH4OH(aq)--> Ca(OH)2(s) + (NH4)2CO3(aq)
CaCO3 + Ba(NO3)2--> Ca(NO3)2+ BaCO3
CaCO3 + Mg(C2H3O2)2-->Ca(C2H3O2)2
+ MgCO3
3CaCO3 + Al2(SO4)3 -->3CaSO4+ Al2(CO3)
Al2(SO4)+6NH4OH-->2Al(OH)
3 +3(NH4)2SO4

and so on and so forth (im not going to bore you with all these letter/numbers)
i got a total of 10combinations because basically i used all of them
i was wondering if you can tell me if that is right/if im balancing the equations right

also, im having a bit of trouble with labeling the state (aq), (s)
[btw, the states i did for the first one are like that for the rest...at least i think so]
please help with some reassurance/corrections of my work, thanks

Answer 1

Your reactions are in the form
[A+B- ] + [C+D- ] = [ A+D- ]+[C+B-]. If the compounds involved are relatively soluble, there will be no precipitate that will remove one compound from solution. This removal "drives" the reaction (see LeChatelier's principle).

You have to find out which compounds are the most insoluble. Your chem book should have a Ksp table somewhere. Without going into the gory details, the most insoluble salts have the highest NEGATIVE exponent in the Ksp.
......BTW
Reactions like the first one just don't happen; a weak base will not react to produce a strong base.

Answer 2

1st one - when a carbonate is being reacted by ammonia, it only produce a little or no ppt. yeah?
2nd - if u uses barium nitrate, most probably for my standered, its used for testing sulphate ions.
3rd - i duno whats that..
4th - i dont know
5th - dont know
ok btw, for Fe2+,Fe3+ and Cu2+ this will produce ppt of Green, Brown and Blue respectively in both Sodium Hydroxide( Na(OH) ) and Liquid Ammonia ( NH4(OH) )..
For Ca2+, when mixed with SodiumHydroxide, white ppt will be produce, insoluble in excess, and when mised with ammonia hydroxide, little or no ppt will be produce.
For Al metal, when mixed with sodium hydoxide, hydogen gas will be produce, when mixed with ammonia hydroxide, ammonia will be produced..
For Zn2+, when mixed with sodium hydroxide, white ppt will be formed, when mixed with ammonia hydroxide, no ppt will be formed..
Think this is all i know already, hope it helps..