n which reactions is the non-metal behaving as an oxidising agent?        I    2KI(aq) + Br2(aq) →→ 2KBr(aq) + I2(aq)       II    CO2(g) + C(s) →→ 2CO(g)      III    3Mg(s) + N2(g) →→ Mg3N2(s)      IV    PbO(s) + H2(g) →→ Pb(s) + H2O(g)AI and III onlyBI and IV onlyCII and III onlyDII and IV only

The correct answer is A. I and III only.

Explanation:

An oxidising agent is a substance that gains electrons in a chemical reaction, causing another substance to be oxidised (lose electrons).

I. 2KI(aq) + Br2(aq) → 2KBr(aq) + I2(aq): In this reaction, Br2 is the oxidising agent. It gains electrons from I- ions to form Br- ions, while the I- ions are oxidised to I2.

II. CO2(g) + C(s) → 2CO(g): In this reaction, CO2 is the oxidising agent. It gains electrons from C to form CO, while the C is oxidised to CO.

III. 3Mg(s) + N2(g) → Mg3N2(s): In this reaction, N2 is the oxidising agent. It gains electrons from Mg to form N3- ions, while the Mg is oxidised to Mg2+ ions.

IV. PbO(s) + H2(g) → Pb(s) + H2O(g): In this reaction, PbO is the reducing agent. It loses electrons to H2 to form Pb and H2O, while the H2 is reduced to H2O.

Therefore, the non-metal is behaving as an oxidising agent in reactions I and III.