From the Rutherford's gold foil experiment one can conclude that nucleus was very small in size, as compared to the atoms. In the experiment Rutherford discovered that, the atom contains a very small nucleus where all of its positive charge of the atom is present.
The answer depends on what substances you were testing, but here are some ideas.
If all of them were white as in the typical experiment, then color is not very useful. If you were allowed to taste them, then a salty taste would be a helpful clue. If the textures were different, some crystals, like salt or sugar and others powdery, like flour or cornstarch, those properties would be helpful. If some dissolved in water,...
It would be solid
hope this helps
MAke two piles and spread them apart
Steam.A pure substance has an unchanging composition,water in the form of steam has an unchanging composition