Question

RODOX EXAMINATION

1. An oxidation-reduction reaction involves the

            (1) sharing of electrons                       (3) transfer of electrons

            (2) sharing of protons                         (4) transfer of protons

2. In this reaction,                       CO→ 2 CO + O₂

                  the oxidation number of carbon changes from:

            (1) 0 to +4                                           (3) +3 to 0      

            (2) +2 to +4                                         (4) +4 to +2

3. Which balanced equation represents a redox reaction?

1. AgNO₃ (aq) +NaCl (aq) →AgCl (s) +NaNO₃ (aq)
2. H₂CO₃ (aq) →H₂O (ℓ) + CO₂ (g)
3. NaOH (aq) + HCl (aq) →NaCl (aq) + H₂O (ℓ)
4. Mg (s) + 2HCl (aq) →MgCl₂ (aq) + H₂ (g)

4. Which ionic equation is balanced? Since all reactions have conservation of mass, look for the one that also has conservation of charge

1. Fe³⁺ + Al → Fe²⁺ + Al³⁺
2. Fe³⁺ + 3 Al → Fe²⁺ + 3 Al³⁺
3. 3 Fe³⁺ + Al → 3 Fe²⁺ + Al³⁺
4. 3 Fe³⁺ + Al → Fe²⁺ + 3 Al³⁺

5. What is the oxidation state of nitrogen in the compound NH₄Br?

            (1) -1                                                   (3) +2             

            (2) -3                                                 (4) +4

           

Which metal is more active than H₂?            

            (1) Ag                                      (3) Au             

            (2) Cu                                      (4) Pb

6. Given the balanced equation representing a reaction:

                        Fe₂O₃ + 2 Al → Al₂O₃ + 2 Fe

      During this reaction, the oxidation number of Fe changes from

1. +2 to 0 as electrons are transferred
2. +2 to 0 as protons are transferred
3. +3 to 0 as electrons are transferred
4. +3 to 0 as protons are transferred

7. In the reaction Sn²⁺ + 2 Fe³⁺ →   Sn⁴⁺ + 2 Fe²⁺, the reducing agent is

           

                  (1)Fe²⁺                                                             (3) Sn²⁺               

            (2) Fe³⁺                                                (4) Sn⁺⁴

           

8. Which half-reaction equation represents the reduction of an iron (II) ion = Fe²⁺

            (1) Fe²⁺ → Fe³⁺ + e⁻                           (3) Fe³⁺ + e⁻ → Fe²⁺

                  (2) Fe²⁺ + 2 e⁻ → Fe                         (4) Fe → Fe²⁺ + 2 e⁻

9. MnSO₄ is a product in a reaction that contained KMnO₄ as a reactant. The oxidation number of the manganese changed from

            (1) -2 to +5                                          (3) +5 to -2

(2) +7 to +2                                         (4) +7 to +2

10. Which is not an oxidation-reduction reaction?

1. 4 Na + O₂ → 2 Na₂O
2. Fe + 2 HCl → FeCl₂ + H₂
3. CaCl₂ + 2 AgNO₃ → 2 AgCl + Ca(NO₃)₂
4. 2 H₂O → 2 H₂ + O₂

11. What is the oxidation number of Cr in Na₂CrO₄     2(+1) + x +   4(-2) = 0

(1) +1                                      (3) +3             

            (2) +2                                      (4) +6

12. During a single displacement reaction, which of the following is true?

1. The more active metal is reduced.
2. The more active metal is oxidized.    
3. The more active metal gains electrons.
4. The less active metal loses electrons.      

15. Which metal can reduce Pb²⁺?           Table J:   higher free metal (Fe)reacts with

            (1) Cu                                      (3) Fe             lower combined metal (Pb⁺²)

            (2) Hg                                      (4) Ag

1.        Zn   +         HCl   à         H₂    +        ZnCl₂                            

Reactants	Products
What is the oxidation number for Zn?     _______ H?       _______ Cl?      _______	What is the oxidation number for Zn?     _______ H?       _______ Cl?      _______
Which element is oxidized?   _______ Which element is reduced?    _______ Which substance is the spectator ion? _______

2.        CH₄    +          NO₂      à          N₂     +     CO₂       +         H₂O                        

Reactants	Products
What is the oxidation number for C?       _______ H?       _______ N?       _______ O?       _______	What is the oxidation number for C?       _______ H?       _______ N?       _______ O?       _______
Which element is oxidized?   _______ Which element is reduced?    _______

Answer 1

involves the 1. Am oxidation - reduction reaction 3) tromsfer of electrons. *co - 2'to +09 . p . This is a wrong reaction. lt The correct reaction will be made. 200 + 02 → 2002 Here, the oxidation number of Carbon changes from +2 to 14 Reduction Mg(s) + 2 Häcap) → kū_caq) + in ca), L O xidation in the This is a redor reaction. l t , The balanced, ionic equation is : t oties Brest + Al 3 Fe 2+ + Al3+ in 3 + NHy Br Here H has +1 oxidation state. . Bt has - Oxicitim state. Lit N Chas x oxidation state. Noti, x,+ 4°C+1),+ (-1) 0 => x = -3, Hence, Oxiclation state of Nitrogen is • Lead rely I pb is more active, than' H₂ Fe2O3 + 2Al Al2O +2 Ferone so oxidation number of fe changes from . +3 to o. as electrons are transfered.

• So2+ Vyp 3 it + 2h + 2h 37 + 2 fel The reducing educting agent agent. is So 2+ (3) SP-0) Reduction of iron (Fe 124) ion is represented by: Fe + 2e s emen alt 2- • The oxidation number of manganese changed from 7 to +2 o As in xMoly 17 +2 ilino, sol insoy . Call + 2 AgNO₃ 2 Agel + Ca(NO3)2 is not an oxidation - reduction reaction. Nл, съоч Vrl2x41) t r t 47-2 = 0 => x = 8.-2.-6 so oxidation Number of cristo. 1. zu ha i nch In is oxidized. H is reduced salaryo ct is spectatorion. 0 ith 2 +4-2 +1 -2 "CHY & No N2 +502 + H₂0 carbon (C) is oxidized. Nitrogen (N) is reduced.