1) Which of the following defines oxidation in terms of electron transfer? (2 answers) a) A. Gain of electrons b) B. Loss of electrons c) C. Increase in oxidation number d) D. Decrease in oxidation number 2) In the reaction: Zn + Cu²⁺ → Zn²⁺ + Cu, which species is oxidised? a) A. Zn b) B. Cu c) C. Cu²⁺ d) D. Zn²⁺ 3) What is the oxidation number of nitrogen in NO₃⁻? a) A. +3 b) B. +2 c) C. +5 d) D. -1 4) What is the oxidation number of oxygen in hydrogen peroxide (H₂O₂)? a) A. -2 b) B. -1 c) C. 0 d) D. +1 5) What is the oxidation number of hydrogen in calcium hydride (CaH₂)? a) A. +1 b) B. -1 c) C. 0 d) D. +2 6) Which of the following statements about oxidising agents is TRUE? a) A. They lose electrons and bring about oxidation b) B. They gain electrons and bring about oxidation c) C. They gain electrons and bring about reduction d) D. They are never involved in redox reactions 7) What is the oxidation number of Mn in MnO₄⁻? a) A. +2 b) B. +4 c) C. +6 d) D. +7 8) In terms of oxidation number, oxidation is defined as: a) A. A decrease in oxidation number b) B. An increase in oxidation number c) C. A constant oxidation number d) D. Transfer of neutrons 9) Which of the following is both an oxidising agent and a bleach? a) A. NaCl b) B. H₂O c) C. NaOCl d) D. H₂SO₄ 10) Which rule is CORRECT for assigning oxidation numbers? a) A. Halogens always have +1 b) B. Oxygen always has +1 c) C. The total of oxidation numbers in a neutral compound is 0 d) D. Hydrogen in all compounds has an oxidation number of -1 11) In balancing redox equations, the number of electrons lost must equal: a) A. The number of electrons gained b) B. The number of protons c) C. The total number of atoms d) D. The charge on the most reactive ion 12) Which of the following represents a reduction in terms of oxidation number? a) Cl₂ → 2Cl⁻ b) Fe²⁺ → Fe³⁺ c) Zn → Zn²⁺ d) H₂ → 2H⁺ 13) In the reaction: Zn + Cu²⁺ → Zn²⁺ + Cu, which substance is the oxidising agent? a) Zn b) Cu c) Zn²⁺ d) Cu²⁺ 14) Which of the following is the correct oxidation number of oxygen in OF₂? a) –2 b) –1 c) 0 d) +2 15) In which compound does hydrogen have an oxidation number of –1? a) A. HCl b) B. H₂O c) C. NH₃ d) D. NaH 16) What is the oxidation number of sulfur in H₂SO₄? a) A. +4 b) B. +6 c) C. –2 d) D. +2 17) What is the oxidation number of nitrogen in NO₃⁻? a) A. +3 b) B. +5 c) C. –3 d) D. +2 18) What is the oxidation number of chlorine in ClO₃⁻? a) A. +3 b) B. +5 c) C. +7 d) D. –1 19) Which of the following definitions of reduction is correct? a) A. Gain of oxygen b) B. Gain of electrons 20) In the redox reaction: Cl₂ + 2Br⁻ → 2Cl⁻ + Br₂, the chlorine is acting as: a) A. A reducing agent b) B. A neutral spectator c) C. An oxidising agent d) D. A catalyst 21) The oxidation number of chromium in Cr₂O₇²⁻ is: a) A. +3 b) B. +6 c) C. +7 d) D. +2 22) What is the oxidation number of an uncombined element like Na or Cl₂? a) A. +1 b) B. –1 c) C. Depends on electronegativity d) D. 0 23) What is the oxidation number of Fe in Fe²⁺? a) A. 0 b) B. +1 c) C. +2 d) D. –2 24) What must the sum of the oxidation numbers in a neutral compound equal? a) A. +2 b) B. 0 c) C. –1 d) D. The group number of the elements 25) What is the oxidation number of oxygen in peroxides (e.g., H₂O₂)? a) A. –2 b) B. –1 c) C. 0 d) D. +2 26) What is the oxidation number of fluorine in any compound? a) A. Depends on what it’s bonded to b) B. Always –1 (most electronegative) c) C. Always 0 d) D. Always +1 27) What is the oxidation number of nitrogen in HNO₃? a) A. +3 b) B. +5 c) C. –3 d) D. +1 28) What is the oxidation number of sulfur in SO₄²⁻? a) A. +2 b) B. +4 c) C. +6 d) D. –2 29) What is the oxidation number of carbon in CO₂? a) A. +2 b) B. +4 c) C. –4 d) D. 0 30) Which element has an oxidation number of 0 in the following species? a) A. Cl in NaCl b) B. O in O₂ c) C. H in HCl d) D. Na in Na⁺ 31) What is the oxidation number of phosphorus in PO₄³⁻? a) A. +3 b) B. +5 c) C. +4 d) D. –3 32) Which of the following compounds contains oxygen with an oxidation number different from –2? a) A. CO₂ b) B. H₂O c) C. H₂O₂ d) D. Na₂O 33) What is the oxidation number of iron in FeCl₃? a) A. +1 b) B. +2 c) C. +3 d) D. –3 34) What is the oxidation number of sulfur in H₂S? a) A. –2 b) B. +2 c) C. 0 d) D. +4 35) What is the oxidation number of nitrogen in NO₂? a) A. +3 b) B. +4 c) C. +5 d) D. –1 36) What is the oxidation number of nitrogen in NH₄⁺? a) A. +1 b) B. –3 c) C. 0 d) D. +3

LC Oxidation Reduction

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