For the first question, its revise the hypothesis and develop a new experiment to test it
For the second question, the fertilizer independent variable
It'd be a physical change. This is because it's a change in the state of matter and not altering the chemical structure of water

If every oxygen ion is combined with an aluminium ion has a charge of -2,the charge of each aluminum ion would be -3.
Uncharged Aluminum atom must need to lose it's electrons,in order to form the bond with oxygen which has vacant orbitals
ion
atom that has a positive or negative charge because it lost or gained one or more electrons
chemical bond
the attractive force that holds atoms or ions together
ionic bond
a chemical bond in which one atom loses an electron and the other atom gains electrons to form ions
chemical formula
a combination of chemical symbols and numbers to represent a substance
covalent bond
bond formed by the sharing of electrons between atoms
<span>In organic chemistry, covalent bonding is most often associated with carbon compounds, which are known as organic chemicals. Hydrogen is also involved most of the time, as well as oxygen. Other elements can also be involved, but less frequently.</span>