A Level Chemistry OCR Practice Exam 2026 – All-in-One Guide to Master Your Chemistry Exam!

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.