Question

1) A double displacement reaction takes place when aqueous sodium carbonate reacts with aqueous tin (II) nitrate. You would expect one of the products of this reaction to be.
Answer: Sn(CO3)2

2) For the reaction, 3 Cu + 8HNO3 --> 3Cu(NO3)2 + 2NO + 4H2O, if you could drop 12 atoms of copper into nitric acid, how many molecules of NO would be produced?
Answer: 8

3) When 2.0 moles of aluminum reacts completely with 3.0 moles of chlorine gas (Cl2) to form aluminum chloride, the total number of moles of the subtances in the system:
Answer: remains the same?

1 and 2 are ok.
3 needs to be redone. Write the equation on a piece of paper and you will see what happens.