What! Â Your teacher is crazy - half of those things will catch on fire if they are mixed! Â You should double check to make sure you have them written down right or you could really get hurt!
If you mix HNO3 and HCl you will get a brown gas (don't light it or smell it!). Â The one that is heavier is the HNO3, because it has more atoms in it. Â Then, mix the silver one (AgNO3) with KOH - it will give a silver coating to the plastic (search for Tollins Test to see what it looks like). Â DI water will absorb CO2 from the air and make carbonic acid, so the one that is acidic will be the water.
Good luck!