Question

Which substance is one that cannot be separated or broken down into simpler substances by chemical means? (Element, pure)

Answer 1

Answer:

gold wire (Au)

Explanation:

A substance that cannot be separated or broken down into simpler substances by chemical means is an element.

Between the given options only gold wire is an element, Au.

A way of knowing that it is an element is noticing that its formula is a single symbol which corresponds to an element found in the periodic table, unlike a combination of said symbols (like NaCl or H₂O).