Asubstance that cannot be broken down into simpler substances by chemical or physical means is called a

Explanation:

An element is a substance that is made up of only one type of atoms. It cannot be broken down into simpler substances.

For example, sodium, aluminium, nickel etc are all elements.

Whereas when two or more different elements combine together then it results in the formation of a compound.

For example, is a compound.

Therefore, we can conclude that a substance that cannot be broken down into simpler substances by chemical or physical means is called an element.

frequency, z, and the collision density, z, in carbon dioxide (co2), r 180 pm at 30 °c and 120 kpa