A Level Chemistry OCR Practice Exam

Which of the following describes an oxidising agent's chemical behavior?

1. It gains electrons during reaction

2. It loses protons during reaction

3. It does not change in mass after reaction

4. It increases the temperature of the reaction

The correct answer is: It gains electrons during reaction

An oxidising agent is characterized by its ability to gain electrons during a chemical reaction. This process involves the oxidising agent itself being reduced while facilitating the oxidation of another species by accepting electrons. In a redox reaction, the oxidising agent typically causes another substance to lose electrons, which means that the oxidising agent undergoes a reduction in its own oxidation state as a result of gaining these electrons. The other statements highlight characteristics that are not typical of an oxidising agent's function. For instance, losing protons is more closely associated with acid-base reactions rather than the behavior of oxidising agents. The mass change post-reaction can vary; although an oxidising agent might not change in mass significantly if it participates in a balanced reaction, this is not a defining characteristic. Likewise, increasing the temperature of a reaction is influenced by various factors such as reaction kinetics and is not inherently a property of oxidising agents. Thus, the primary behavior of an oxidising agent is accurately captured by the statement that it gains electrons during a reaction.