Match List I (Oxidation number) with List II (The element) and select the correct answer using the codes given below this lists: List I (Oxidation number) - List II (The element) 1. A. 2 - 1. Oxidation number of Mn in MnO2 2. B. 3 - 2. Oxidation number of S in H2S2O7 3. C. 4 - 3. Oxidation number of Ca in CaO2 4. D. 6 - 4. Oxidation number of Al in NaAIH4

1. This question requires matching the oxidation number (oxidation state) of a specific element in a given compound. 2. A. Target: Oxidation number = 2. Let's check the options: (1) Mn in MnO2: Oxygen is usually -2. 2x(-2) = -4. So Mn must be +4. (2) S in H2S2O7 (Pyrosulfuric acid): H is +1, O is -2. 2x(+1) + 2x(S) + 7x(-2) = 0 => 2 + 2S - 14 = 0 => 2S = 12 => S = +6. (3) Ca in CaO2 (Calcium peroxide): Ca is an alkaline earth metal, always +2 in compounds. Oxygen here is in peroxide form (O2^2-), so each O is -1. (4) Al in NaAlH4: Na is +1, H is usually +1 but -1 in metal hydrides. Here Al is bonded to Na and H, suggesting H is -1 (hydride). +1 + Al + 4x(-1) = 0 => 1 + Al - 4 = 0 => Al = +3. Thus, Ca in CaO2 has an oxidation number of +2. Matches A with 3. 3. B. Target: Oxidation number = 3. From above, Al in NaAlH4 has an oxidation number of +3. Matches B with 4. 4. C. Target: Oxidation number = 4. From above, Mn in MnO2 has an oxidation number of +4. Matches C with 1. 5. D. Target: Oxidation number = 6. From above, S in H2S2O7 has an oxidation number of +6. Matches D with 2. 6. Therefore, the correct matching is A-3, B-4, C-1, D-2.