Match List-I (Oxidation number) with List II (The element) and select the correct answer using the codes given below the lists: List-I (Oxidation number) List-II (The elements) A. 2 1. Oxidation number of Mn in MnO2 B. 3 2. Oxidation number of S in H2S2O7 C. 4 3. Oxidation number of Ca in CaO D. 6 4. Oxidation number of Al in NaAlH4 Codes:

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YESPYQ · Accepted Answer

Correct answer: A-3; B-4; C-1; D-2. The oxidation number indicates the oxidation state of an element in a compound, reflecting the number of electrons lost or gained relative to its neutral atom. The oxidation number formula is based on the principle that the algebraic sum of the oxidation numbers of all atoms in a molecule or ion equals the overall charge of the compound or ion. It is equal to zero for a neutral compound . A is matched with 3: In CaO, oxygen has an oxidation number of –2. Since the compound is neutral, the oxidation number of calcium(Ca) is calculated as: x + 1(−2) = 0 ⇒ x = +2. B is matched with 4 : In NaAlH₄, sodium is +1, hydrogen (as a hydride) is -1, and the oxidation number of aluminium(Al) is calculated as: 1(+1) + x + 4 (−1) = 0 ⇒ x = +3. C is matched with 1: In MnO₂, oxygen has an oxidation number of –2, so for manganese(Mn): x + 2(−2) = 0 ⇒ x = + 4. D is matched with 2: In H₂S₂O₇, hydrogen is +1, oxygen is -2, and sulfur(S)’s oxidation number is calculated as: 2(+1) +2(x) +7(−2) = 0 ⇒ 2 + 2x−14 = 0 ⇒ x = +6. . 327

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