A substance you can't physically change would be copper grains, and iron filings.
an Element
^incorrect, a pure substance
A Compound is a chemically combined entity. It cannot be separated physically. A Solution is a physically combined entity. Hence, it can be separated physically.
Substance, classified as an element and compound. For an element, it cannot be separated into another simplier substance; for a compound, it can be dicomposed into elements using chemical processes.
The iron cannot be mechanically separated from it's oxide. The compounds [Fe2O3·nH2O, FeO(OH), Fe(OH)3] called "rust" are difficult to separate chemically into iron water and oxygen.
gelato
molecules
Any substance or compound cannot be physically separated. The broad term for this is simply "substance".
It's a compound
What are the components of solutions?
The substance is a compound, which forms chemical bonds that cannot be physically separated, but only by a chemical change.
Elements
Sugar
A substance that is chemically combined cannot be separated physically.In some situations, you can and can't separate combined substances physically. For example, you can separate sand from rocks physically, but you cannot separate water and ice cream, even though the substances did not undergo a chemical change, because the water soaked into the ice cream.
A pure substance.
A Compound is a chemically combined entity. It cannot be separated physically. A Solution is a physically combined entity. Hence, it can be separated physically.
A compound.
It is a mixture of many, many different substances.
An element cannot be separated into simpler substances by chemical means.