Like dissolves like
Two experiments have now shown that the solute and the solvent both matter, without saying what about them matters. The answer is something you met in grade 10.
The solubility of a substance is decided by the nature of the molecules it is made of, and the property that counts is one you already know: the polarity of the chemical bonds in it. Grade 10 divided compounds into polar and non-polar on exactly this basis, and separately into organic and inorganic by whether they contain carbon. Put the two divisions together and you get four kinds.
Four kinds of solvent and solute
Every solvent and every solute in this chapter falls into one of these.
Polar organic
Alcohol, formalin, acetone
Non-polar organic
Hexane, benzene, carbon tetrachloride
Polar inorganic
Water, ammonia, hydrogen chloride
Non-polar inorganic
Carbon disulphide, liquid carbon dioxide
The rule that follows
The rule
substances of similar polarity dissolve in one another
like dissolves like
Polar solutes dissolve in polar solvents
Ethanol is a polar compound and water is a polar compound, so ethanol dissolves in water.
Ammonia is a polar compound and water is a polar compound, so ammonia dissolves in water.
Non-polar solutes dissolve in non-polar solvents
Grease is a non-polar solute and kerosene is a non-polar solvent, so grease dissolves in kerosene.
Soot is a non-polar solute and kerosene is a non-polar solvent, so soot dissolves in kerosene.
Why the sugar failed in kerosene
Sugar is polar and kerosene is non-polar, so they are not alike and the sugar stays undissolved. The same rule explains why grease will not wash off in water but comes away with kerosene.