heterogeneous mixture is two or more unlike substances mixed together. Example would be salt and sugar mixture, or salt and pepper. You can have the same sunstance but in different phases such as water and ice. A substance like milk is said to be homogenous ( the same substance) after homogenization but it is actually a heterogenous mixture of calcium, fat, water and various other substances that don't readily return to its original state.
Sand+salt: a heterogeneous mixture.
Oxygen is a chemical compound, not a mixture.
Heterogenous mixture
Oxygen is a chemical element not a mixture.
Lead is a chemical element, not a mixture.
dirt is a mixture
Neptunium is a chemical element.
A salt is a chemical compound.
Sugar is a chemical compound.
Sugar is a chemical compound, not a mixture.
Heterogeneous mixture.
Mercury is a chemical element not a mixture.