PLEASE HELP ME WITH THESE CHEMISTRY EQUATIONS!

[electronaut859]

This is part of my homework for chemistry class and I don't understand how to do it. I have to: Balance the chemical equation and write what state of matter it is in.

3. H₂ (g) + O₂ (g) are involved in a synthesis reaction.

4. Ag₂O (s) is involved in a decomposition reaction.

5. Ca(OH)₂ (aq) + HCl (aq) are involved in a double replacement reaction.

6. NaCl (aq) + H₂SO₄ (aq) are involved in a double replacement reaction.

7. MgBr₂ (aq) + Cl₂ (g) are involved in a single replacement reaction.

8. Cu (s) + AgNO₃ (aq) are involved in a single replacement reaction.

9. Cl₂ (g) + LiI (aq) are involved in a single replacement reaction.

PLEASE PLEASE PLEASE HELP!