Question

what is a substance that cannot be broken down chemically into a simpler substance?
○ a molecule
○ a compound
○ an atom
○ an element

Explanation:

• A molecule can be broken down into atoms chemically.
• A compound is made of multiple elements and can be split into simpler substances via chemical reactions.
• An atom is the smallest unit of an element, but the question refers to a substance, not a particle.
• An element is a pure substance that cannot be broken down into simpler substances through chemical means.

Answer:

D. an element