Answer:
reactions between air, water and minerals, chemicals in rain water
The last one is the answer I think
Heat up the solvent. This will cause the molecules of the solvent to become more energized and "expand" to allow for more solvent to be added. However, once the solvent cools down, the extra solute may fall out as a precipitate.
This is how rock candy is made, by the way.
Answer:
4NH3+6NO=5N2+6H2O
search equation balancer on the internet and you will find the answer