Here's a breakdown:

Compounds that can be separated by physical means:

* Mixtures: These are combinations of substances that are not chemically bonded. They can be separated by physical means like:

* Filtration: Separating solids from liquids using a filter.

* Evaporation: Separating a dissolved solid from a liquid by heating and allowing the liquid to evaporate.

* Distillation: Separating liquids with different boiling points.

* Magnetism: Separating magnetic solids from non-magnetic ones.

* Decantation: Separating a liquid from a denser solid or a lighter liquid by carefully pouring off the top layer.

Compounds that cannot be separated by physical means:

* True compounds: These are formed by the chemical combination of two or more elements in a fixed ratio. They require chemical reactions to break them down into their constituent elements.

Examples:

* Salt (NaCl): A compound that can be separated by electrolysis (a chemical process).

* Water (H2O): A compound that can be separated by electrolysis.

* Sand and water: A mixture that can be separated by filtration.

* Saltwater: A mixture that can be separated by evaporation.

Important Note: Some compounds may appear to be separable by physical means, but the process actually involves a chemical change. For example, heating sugar may seem like a physical change, but it's actually a chemical decomposition reaction that breaks down the sugar into simpler compounds.

So, the key is to understand whether the substances are chemically bonded (compounds) or simply mixed together.