3 Sn⁴⁺_(aq) + 2 Cr_(s) 3 Sn²⁺_(aq) + 2 Cr³⁺_(aq)

Which half-reaction represents the reduction that occurs?
a) Sn⁴⁺_(aq) + 2 e^- Sn²⁺_(aq)
b) Sn²⁺_(aq)  Sn⁴⁺_(aq) + 2 e^-
c) Cr_(s) Cr³⁺_(aq) + 3 e^-
d) Cr³⁺_(aq) + 3 e^- Cr_(s)

2. What is the oxidation number of nitrogen in N₂?
a) +1
b) 0
c) +3
d) -3

3. Given the reaction:

Zn_(s) + 2 HCl_(aq) ZnCl_2(aq) + H_2(g)

Which substance is oxidized?
a) Zn_(s)
b) HCl_(aq)
c) Cl^-_(aq)
d) H⁺_(aq)

4. A redox reaction always demonstrates the conservation of
a) mass, only
b) charge, only
c) both mass and charge
d) neither mass nor charge

5. Given the balanced reaction:

2 Al_(s) + 6 H⁺_(aq) 2 Al³⁺_(aq) + 3 H_2(aq)

What is the total number of moles of electrons gained by H⁺_(aq) when 2 moles of Al_(s) is completely reacted?
a) 6
b) 2
c) 3
d) 12

6. In an electrolytic cell, the negative electrode is called the
a) anode, at which oxidation occurs
b) anode, at which reduction occurs
c) cathode, at which oxidation occurs
d) cathode, at which reduction occurs

7. The diagram below represents an electrochemical cell.

What occurs when the switch is closed?
a) Zn is reduced.
b) Cu is oxidized
c) Electrons flow from Cu to Zn.
d) Electrons flow from Zn to Cu.

8. In an electrochemical cell, what is the purpose of the salt bridge?
a) It is the anode.
b) It is the cathode.
c) It permits the migration of ions between the half-cells.
d) It permits the mixing of solutions between the half-cells.

9. What are the two oxidation states of nitrogen in the compound NH₄NO₃?
a) -3 and -5
b) -3 and +5
c) +3 and -5
d) +3 and +5

10. Given the redox reaction:

Mg_(s) + CuSO_4(aq) MgSO_4(aq) + Cu_(s)

Which species acts as the oxidizing agent?
a) Cu_(s)
b) Cu²⁺_(aq)
c) Mg_(s)
d) Mg²⁺_(aq)

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