  Before it rains, if using granular fertilizer, so that it will melt into the soil and become available for use by the plant roots.....IF you are using liquid fertilize â¦ r you would apply it either on the leaves, or by drenching the soil around the plant at least 24 hours before a rain occurs. Before it rains, if using granular fertilizer, so that it will melt into the soil and become available for use by the plant roots.....IF you are using liquid fertilize â¦ r you would apply it either on the leaves, or by drenching the soil around the plant at least 24 hours before a rain occurs.
There are two possible definitions for Physical and Chemical changes which I use in school: 1. A physical change is reversible, a chemical change is not. For example, the freezing of water would be a physical change because it can be reversed, whereas the burning of wood is a chemical change - you can't 'unburn' it. 2. A physical change is a change in which no new substance is formed; a chemical change results in the formation of one or more new substances. Again, consider the previous examples: Freezing water into ice just results in water molecules which are 'stuck' together - it's still H2O.
So, in summary, there are really only two criteria for whether a change is chemical or physical: 1) After the change does it look the same and 2) can you change it back? If the answer is yes, the change is physical every time. If the answer is no the change is chemical every time.