In a single-displacement reaction, which statement best describes the event?

In a single-displacement reaction, which statement best describes the event?

• A. Two compounds exchange ions
• B. A compound decomposes into simpler substances
• C. A hydrocarbon and oxygen form water and CO2
• D. One element or radical replaces another

Answer: (D)

In a single-displacement reaction, one element replaces another in a compound to form a new compound and a free element. The driving idea is that a more reactive element can kick out a less reactive one from its compound. The general pattern is A + BC → AC + B, where the single element A takes the place of B in the compound BC. This is an oxidation‑reduction process, often seen with metals: a more reactive metal displaces a less reactive metal from a salt solution, moving electrons from the metal to its ion. A classic example is zinc reacting with copper(II) sulfate: Zn + CuSO4 → ZnSO4 + Cu. Here zinc displaces copper, forming zinc sulfate and solid copper. Why the other descriptions don’t fit: exchanging ions between two compounds describes a double-displacement reaction, not single displacement. Decomposition refers to a compound breaking apart into simpler substances. Combustion involves a hydrocarbon reacting with oxygen to form water and carbon dioxide.

In a single-displacement reaction, one element replaces another in a compound to form a new compound and a free element. The driving idea is that a more reactive element can kick out a less reactive one from its compound. The general pattern is A + BC → AC + B, where the single element A takes the place of B in the compound BC. This is an oxidation‑reduction process, often seen with metals: a more reactive metal displaces a less reactive metal from a salt solution, moving electrons from the metal to its ion. A classic example is zinc reacting with copper(II) sulfate: Zn + CuSO4 → ZnSO4 + Cu. Here zinc displaces copper, forming zinc sulfate and solid copper.

Why the other descriptions don’t fit: exchanging ions between two compounds describes a double-displacement reaction, not single displacement. Decomposition refers to a compound breaking apart into simpler substances. Combustion involves a hydrocarbon reacting with oxygen to form water and carbon dioxide.