Chemistry equations HELP?

Question

PLS balance the following equation:

Fe + O2 + H2O becomes Fe2O3 . xH2O

Fill the "?"

Mg + CaCO3 becomes ?

nonmetal + base = ?

Is metal + acid = salt +H2 ?

Is metal + base = complex compound + H2 ?

Answer 1

1.  4Fe +3O2 + 2xH2O -> 2Fe2O3 . xH2O.

2.  No reaction.  A nonmetal may react with a base; what you get out depends on what you put in.

3. Normally, yes.

4. This varies, depending on the reactants.