Question

which identifies an oxidation-reduction reaction?
a double replacement reaction
a neutralization reaction
a reaction in which oxidation numbers change
a reaction in which no electrons are transferred

Explanation:

• A double - replacement reaction (e.g., \(AB + CD=AD + CB\)) involves the exchange of ions between compounds. In most cases, the oxidation numbers of the elements remain the same, so it is not an oxidation - reduction reaction.
• A neutralization reaction is a reaction between an acid and a base to form a salt and water (e.g., \(HCl+NaOH = NaCl + H_2O\)). The oxidation numbers of the elements involved do not change, so it is not an oxidation - reduction reaction.
• By definition, an oxidation - reduction (redox) reaction is a chemical reaction in which the oxidation numbers of the atoms involved change. This change in oxidation numbers is associated with the transfer of electrons (oxidation is the loss of electrons and reduction is the gain of electrons).
• A reaction in which no electrons are transferred cannot be an oxidation - reduction reaction, because electron transfer is a key characteristic of redox reactions.

Answer:

C. a reaction in which oxidation numbers change