The formation of a single element and a compound from a different element and compound is called

• A. Double-Replacement
• B. Synthesis
• C. Decomposition
• D. Single-Replacement

Answer: (D)

In a single-replacement reaction, a free element reacts with a compound and replaces one of the elements in that compound, producing a new element and a new compound. For example, zinc metal reacting with copper(II) sulfate gives zinc sulfate and copper: Zn + CuSO4 → ZnSO4 + Cu. This shows how an elemental partner can displace a portion of a compound to form a different element and a different compound, with reactivity determining whether the displacement happens.

Synthesis would involve two or more substances combining to form one more complex compound (A + B → AB). Decomposition is the opposite, where a compound breaks apart into simpler substances (AB → A + B). Double-replacement involves two compounds exchanging partners to form two new compounds (AB + CD → AD + CB).