Which of the following is a substance made up of two or more different elements bonded together?

• A. Element
• B. Pure substance
• C. Mixture
• D. Compound

Answer: (D)

When two or more different elements bond together, they form a compound. This happens through chemical bonds that lock the elements into a fixed ratio, producing a substance with properties different from each element on its own. That distinguishes a compound from an element, which is just one kind of atom, and from a mixture, where substances are only physically combined and can have varying compositions with no chemical bonds holding them together. A pure substance can be either a single element or a compound, but the description here specifically points to a compound because it involves bonding between different elements.