Answer :
Since water and soil are not chemically combined, they are not combining in a fixed ratio, therefore they form a heterogenous mixture.
Chemically combined systems do so in fixed ratios, such as 2H+ ions for every 1 O2- ion to form water molecules.
Chemically combined systems do so in fixed ratios, such as 2H+ ions for every 1 O2- ion to form water molecules.