Any inert gas like Helium, Argon, etc should be a pure substance since it does not react with any other element. Also, it is possible to separate it from the air and store in cylinders. Argon is used to fill electric bulbs otherwise the heated filament inside the bulb would burn in the presence of the oxygen in the air. Therefore these inert gases are examples of "Pure" substance
Examples of pure substance: gold, silver, carbon dioxide, hydrogen
Foods are not pure substances.
Pure substance can be identified as either elements or compounds. Some examples of pure substance that are elements are sulfur and tin. Pure substances that are compounds are sugar and salt.
Water
Salt. Carbon, if you have a carbon filter for your fish tank.
Water is a compound. A pure metal is an element. Graphite (a pencil lead) is the element carbon. These are all examples of a pure substance.
Salt. Carbon, if you have a carbon filter for your fish tank.
pure substance, propanone
it is a pure substance.... not
Pure substance
A pure substance is the same throughout. When a substance is 100% something it is pure.
Methane is a pure substance.