[Figure: the reaction \(\mathrm{2H_2S + SO_2 \rightarrow 3S\downarrow + 2H_2O}\) with an arrow A drawn above, from the reactants towards the products, and an arrow B drawn below, from the products back towards the reactants.](a) Identify the above ch…

Answer: (a) It is a redox (oxidation–reduction) reaction; (b) A – oxidation, B – reduction.

(a) In this reaction hydrogen sulphide and sulphur dioxide react to give sulphur and water. One reactant is oxidised and the other is reduced at the same time, so it is a redox reaction.

(b) In H₂S the oxidation state of sulphur is –2 and it rises to 0 in sulphur, so H₂S is oxidised (arrow A). In SO₂ the oxidation state of sulphur is +4 and it falls to 0, so SO₂ is reduced (arrow B).