Question

Two substances, A and Z, are to be identified. Substance A can not be broken down by a chemical change. Substance Z can be broken down by a chemical change. What can be concluded about these substances?
(1) Both substances are elements.
(2) Both substances are compounds.
(3) Substance A is an element and substance Z is a compound.
(4) Substance A is a compound and substance Z is an element.

Answer 1

The answer is (3) Substance A is an element and Z is a compound. The chemical reaction can only break the chemical bond but can not change the atom. So A will is an element. 

Answer 2

Answer;

(3) Substance A is an element and substance Z is a compound.

Explanation;

-A compound is a substance formed when two or more chemical elements are chemically bonded together, such as water, carbon dioxide, methane, etc while an element is a pure chemical substance made of same type of atoms, such includes, oxygen, potassium, hydrogen, carbon, etc.

- Compounds can be broken down or decomposed into simpler substances: elements cannot be broken down chemically into simpler substances .