Question

in an oxidation - reduction reaction, the substance reduced always ________. gains electrons loses electrons takes an oxygen atoms gives up hydrogen atoms becomes a charged species

Explanation:

In oxidation - reduction (redox) reactions, the process of reduction is defined as the gain of electrons. When a substance is reduced, its oxidation state decreases because electrons are negatively charged. For example, in the reaction \(Cu^{2+}+2e^-\to Cu\), \(Cu^{2+}\) gains electrons and is reduced to \(Cu\).

• Loss of electrons is oxidation.
• Taking an oxygen atom is not the general definition of reduction (e.g., in \(H_2 + F_2=2HF\), there is no oxygen transfer, but \(F_2\) is reduced).
• Giving up hydrogen atoms is not the general definition of reduction (e.g., in \(Cl_2 + 2NaBr = 2NaCl+Br_2\), \(Cl_2\) is reduced without hydrogen atom transfer).
• Becoming a charged species is not specific to reduction (e.g., when \(Na\) becomes \(Na^+\) (oxidation), it also becomes a charged species).

Answer:

gains electrons