Consider the following pairs of reactions and properties: Reactions Properties I. Fe(s) + 2 HCl(aq) FeCl _2 (aq) + H _2 (g) Fe is reductant II. Zn(s) + CuSO _4 (aq) ZnSO _4 (aq) + Cu(s) Cu is being reduced III. Br _2 (l) + 2 I ^- (aq) 2 Br ^- (aq) + I _2 (s) Br _2 is reductant IV. CH _4 (g) + 2 O _2 (g) CO _2 (g) + 2 H _2 O(l) C atom in CH _4 is oxidized Which of the above pairs are correct?
C. I, II and IV
Reaction I: Fe changes its oxidation state from 0 to +2. It undergoes oxidation and acts as a reductant. Pair I is correct. Reaction II: Cu in CuSO _4 changes its oxidation state from +2 to 0. It undergoes reduction. Pair II is correct. Reaction III: Br _2 changes its oxidation state from 0 to -1. It undergoes reduction and acts as an oxidant, not a reductant. Pair III is incorrect. Reaction IV: C in CH _4 changes its oxidation state from -4 to +4. It undergoes oxidation. Pair IV is correct. Therefore, pairs I, II, and IV are correct.
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