Which substance cannot be broken down by a chemical change brutanal, propene, gold, and water

Gold

Explanation:

We cannot break down elements by a chemical change.

Gold is the only element in the list

Butanal, propene, and water are wrong. They are compounds, so they can be broken down into their elements.

Explanation:

Gold cannot be broken down by any physical or chemical methods, because it is an element. It has properties of an element not a compound nor mixture.

Gold is a chemical element with the symbol Au and atomic number 79.

ca has a crystalline lattice with positive ions (since it is a metal, metals are positively charged) and electrons flow freely in its structure since the ca atoms have a large nuclear radius so the electrons are not tightly held, therefore the electrons can flow freely since they are not being highly attracted by the nucleus. moreover, one of the properties of metals are that they are conductors of electricity, thus proving ca is the element.