Consider the reaction $2\mathrm{Na}(s) + \mathrm{Cl}_2(g) \rightarrow 2\mathrm{NaCl}(s)$. Identify the oxidising agent and the reducing agent.

1. Write the two half-reactions: $2\mathrm{Na} \rightarrow 2\mathrm{Na}^+ + 2\mathrm{e}^-$ (oxidation) and $\mathrm{Cl}_2 + 2\mathrm{e}^- \rightarrow 2\mathrm{Cl}^-$ (reduction). 2. Na donates electrons, so Na is OXIDISED, which makes it the reducing agent (donor of electrons). 3. $\mathrm{Cl}_2$ accepts electrons, so $\mathrm{Cl}_2$ is REDUCED, which makes it the oxidising agent (acceptor of electrons). 4. Options A and C invert these roles; D is wrong because Na's oxidation state goes only one direction (0 → +1). _Source: NCERT Class 11 Chemistry Part 2, Ch 7, §7.2, p. 2 ¶8._