Redox Quiz #2


1. Which of the following pairs of ions will react spontaneously in a solution?

A. Cu2+ and Fe2+

B. Pb2+ and Sn2+

C. Co2+ and Cr2+

D. Mn2+ and Cr2+


2. When NO2 reacts to form N2O4 the oxidation number of nitrogen

A. increases by 2

B. increases by 4

C. increases by 8

D. does not change


3. Consider the following redox equation:

12H+(aq) + 2IO3-(aq) + 10Fe2+(aq) → 10Fe3+(aq) + I2(s) + 6H2O(l)

The reducing agent is

A. I2

B. H+

C. Fe2+

D. IO3-


4. The oxidation number of nitrogen increases in


A. NO3- → NO

B. N2O4 → NI3

C. NH3 → NH4+

D. NO2 → N2O5


5. Which of the following represents a balanced reduction half-reaction?

A. VO2 + 2H+ + 2e- → V2+ + H2O

B. VO2 + H2 V2+ + H2O + le-

C. VO2 + 2H+ + le- → V2+ + H2O

D. VO2 + 4H+ + 2e- → V2+ + 2H2O


6. Consider the following half reaction:

Sb2O3 + 6H+ + 6e- 2Sb + 3H2O

The oxidation number of antimony in Sb2O3

A. increases by 3

B. increases by 6

C. decreases by 3

D. decreases by 6


7. Consider the following unbalanced half-reaction


The balanced half-reaction would have

A. 1 electron on the left

B. 1 electron on the right

C. 2 electrons on the left

D. 2 electrons on the right


8. The oxidation number of platinum in Pt(H2O)42+ is

A. +2

B. 0

C. +4

D. +1/2


9. Consider the following half-reaction :

BrO- → Br- (basic)

The balanced equation for the half-reaction is

A. BrO- + 2H+ + 2e- → Br- + H2O

B. BrO- + 2H+ → Br- + H2O + 2e-

C. BrO- + H2O → Br- + 2OH- + 2e-

D. BrO- + H2O + 2e- → Br- + 2OH-


10. Consider the following redox reaction:

2MnO4- + 5CH3CHO + 6H+ → 5CH3COOH + 2Mn2+ + 3H2O

The species that loses the electron is

A. H2O

B. MnO4-




11. Hydrogen has an oxidation number of 1 in

A. H2

B. NaH

C. H2O



12. Consider the following:

2NO3- + 4H+ + 2e- → N2O4 + 2H2O

This equation represents

A. reduction

B. oxidation

C. neutralization

D. decomposition

13. Which of the following half-reactions is balanced?

A. IO3- + 6H+ +5e- → I2 + 3H2O

B. IO3- + 6H+ + 4e- →1/2 I2 + 3H2O

C. IO3- + 6H+ → I2 + 3H2O + 5e-

D. IO3- + 6H+ + 5e- → I2 + 3H2O


14. Consider the following redox reaction:

Al + MnO4- + 2H2O →Al(OH)4- + MnO2

The chemical species being oxidized is

A. Al

B. MnO4-

C. Al(OH)4-

D. MnO2


15. Consider the following redox reaction:

6H+ + 6I- + ClO3- → 3I2 + 3H2O + Cl-

The reducing agent is

A. I-

B. I2

C. H+

D. ClO3-


16. Nitrogen has an oxidization number of zero in

A. N2

B. NO2

C. NH3



17. When MnO4- reacts to form Mn2+, the manganese in MnO4- is

A. reduced as its oxidation number increases

B. reduced as its oxidation number decreases

C. oxidized as its oxidation number increases

D. oxidized as its oxidation number decreases


18. Consider the following reaction:

2HNO3 + 3H2S → 2NO + 3S + 4H2O

The nitrogen in HNO3 undergoes

A. reduction

B. oxidation

C. electrolysis

D. neutralization


19. The oxidation number in carbon in CaC2O4 is

A. +2

B. +3

C. +4

D. +6


20. Consider the following redox reaction:

2Cr3+(aq) + 3Cl2(aq) + 7H2O(l) → Cr2O72-(aq) + 6Cl-(aq) + 14H+(aq)



The species which loses electrons is

A. Cl2

B. Cr3+

C. H2O

D. Cr2O72-


21. Which equation represents a redox reaction?

A. Pb2+ + 2Cl- PbCl2

B. CaO + CO2 → CaCO3

C. Mg + 2HCl → MgCl2 + H2

D. HCl + NaOH → NaCl + H2O


22. In a redox reaction, ClO- was converted to Cl- in a basic solution. The balanced

half-reaction for this process is

A. ClO- + H2O + 2e-Cl- + 2OH-

B. ClO- + 2OH-Cl- + 2e- + H2O

C. ClO- + H2O → Cl- + 2e- + 2OH-

D. ClO- + 2OH- + 2e-Cl- + H2O


23. Which of the following equations is not predicted to represent a redox reaction?
A. 2 H2O(l) + O2(g) 2 H2O2(l)
B. 2 Sn2+(aq) Sn(s) + Sn4+(aq)
C. Ag+(aq) + Cl-(aq) AgCl(s)
D. C2H4(g) + 3 O2(g) 2 CO2(g) + 2 H2O(g)


24. The metal molybdenum, Mo, can react to produce MoO2(s). The half reaction that explains the change in oxidation state of

molybdenum can be written
A. Mo(s) + 2e- Mo2+
Mo(s) Mo2+ + 2e-
Mo4+ + 4e- Mo(s)
D. Mo(s) Mo4+ + 4e-

Which incomplete half-reaction is an oxidation?

A. 2H+ + 12 O2(g) H2O(l)
B. Cr2O72- + 14H+ 2 Cr3+ + 7 H2O(l)
C. K+ K(s)
2 I- I2(s)

26. Which of these would react spontaneously with Co(s) but not with H2(g)?
A. H2O(l)
B. Ni2+(aq)
C. Ca2+(aq)
D. Br-(aq)

27. The chemical that will reduce copper (II) ions and also oxidize metallic nickel is

A. iron (III) nitrate
B. tin (II) sulfate
C. iron (II) nitrate
D. zinc sulfate

28. F2(g) is a strong reducing agent F2(g) has a strong attraction for electrons. Based onthis information, one should determine that

            A. the statement and the explanation are true, and that the explanation is

            correct for the statement.
B. both the statement and the explanation are true, but the explanation is not

            correct for the statement.
C. the statement is true, but the explanation is false.
D. the statement is false, but the explanation is true



29. Solutions containing Fe2+(aq), Sn2+(aq) and Cr2+(aq) are mixed together. The reaction

most likely to occur is
A. 2Fe2+(aq) + 2 H2O(l) Fe(s) + O2(g) + 4H+(aq)
B. Sn2+(aq) + 2Cr2+(aq) Sn(s) + 2 Cr3+(aq)
C. Sn2+(aq) + Cr2+(aq) Sn4+(aq) + Cr(s)
D. Sn2+(aq) + 2 Fe2+(aq) Sn(s) + 2 Fe3+(aq)


30. Four reducing agents listed in order of decreasing strength are W, Z, Y and X. Four statements about the reaction

between the reducing agents and their respective oxidizing agents are:
I. W(s) + X2+(aq) W2+(aq) + X(s)
II. Y(s) + X2+(aq) Y2+(aq) + X(s)
III. W(s) + Z2+(aq) no reaction
IV. Y(s) + Z2+(aq) Y2+(aq) + Z(s)
The statement(s) inconsistent with the correct order of reducing agents is (are)
A. IV only
III only
I and II
III and IV