Question 1

Which of the following best describes an oxidation–reduction (redox) reaction?

Accepted Answer

A reaction in which electrons are transferred from one substance to another.

Question 2

Which of the following reactions is NOT a redox reaction?

Accepted Answer

$$\mathrm{Pb(NO_3$)_2(aq) + 2LiCl(aq) \rightarrow $$PbCl_2$$(s) + 2LiNO_3(aq)}$$

Question 3

In the reaction $$\mathrm{C(s) + 2S(s) \rightarrow CS_2$(l)}$$, what is the oxidation state change for carbon?

Accepted Answer

0 to +4

Question 4

Which of the following is always true for the oxidizing agent in a redox reaction?

Accepted Answer

It is reduced.

Question 5

Assign the oxidation state to nitrogen in $$\mathrm{NO_3$^-}.$$

Accepted Answer

+5

Question 6

Which element is being reduced in the reaction $$\mathrm{2Al(s) + 3Sn$$^{2+}$$(aq) \rightarrow 2Al$$^{3+}$$(aq) + 3Sn(s)}$$?

Accepted Answer

Tin

Question 7

What is the oxidation state of sulfur in $$\mathrm{SO_2$}$$?

Accepted Answer

+4

Question 8

Which of the following best describes the role of the salt bridge in a galvanic (voltaic) cell?

Accepted Answer

It allows ions to flow and neutralize charge buildup in the half-cells.

Question 9

Which of the following metals will NOT react spontaneously with $$\mathrm{Cu$$^{2+}$$(aq)}$$ ions, based on the activity series?

Accepted Answer

Ag

Question 10

Balance the following redox reaction in acidic solution: $$\mathrm{Fe$$^{2+}$$(aq) + $$MnO_4$$^-(aq) \rightarrow Fe$$^{3+}$$(aq) + Mn$$^{2+}$$(aq)}. $$What is the coefficient for $$\mathrm{H^+} in $$the balanced equation?

Accepted Answer

8

Question 11

Which of the following is the correct half-reaction for the reduction of silver ion in aqueous solution?

Accepted Answer

$$\mathrm{Ag^+(aq) + e^- \rightarrow Ag(s)}$$

Question 12

In the reaction $$\mathrm{2H_2(g) + O_2$(g) \rightarrow 2H_2O(g)}$$, which element is oxidized?

Accepted Answer

Hydrogen

Question 13

Which of the following rules is NOT correct for assigning oxidation states?

Accepted Answer

The oxidation state of hydrogen is always -1.

Question 14

Which of the following is a double-displacement reaction?

Accepted Answer

$$\mathrm{AB + CD \rightarrow AD + CB}$$

Question 15

In the reaction $$\mathrm{Zn(s) + Cu$$^{2+}$$(aq) \rightarrow Zn$$^{2+}$$(aq) + Cu(s)}$$, what is the reducing agent?

Accepted Answer

Zn(s)

Question 16

Which of the following statements about combustion reactions is correct?

Accepted Answer

They always produce water and an oxygen-containing compound.

Question 17

What is the oxidation state of carbon in $$\mathrm{CO_2$}$$?

Accepted Answer

+4

Question 18

Which of the following best describes what happens at the anode in a galvanic cell?

Accepted Answer

Oxidation occurs and electrons are lost.

Question 19

Which of the following is the correct order of steps for balancing a redox reaction using the half-reaction method?

Accepted Answer

Assign oxidation states, separate into half-reactions, balance elements, balance O with $$\mathrm{H_2O}$$, balance H with $$\mathrm{H^+}$$, balance charge with electrons, combine and verify.

Oxidation–Reduction (Redox) Reactions: Classification, Oxidation States, and Balancing

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