Name ____________________________________________________
Unit 11: Redox
Date ___________________________________
Multiple Choice Questions
1. What is the oxidation number of manganese in KMnO4?
(1) +7
(2) +2
(3) +3
(4) +4
2. What is the oxidation number of chromium in the chromate ion, CrO4-2?
(1) +6
(2) +2
(3) +3
(4) +8
3. An oxidation-reduction reaction involves the
(1) sharing of electrons
(2) sharing of protons
(3) transfer of electrons
(4) transfer of protons
4. When a neutral atom undergoes oxidation, the atom’s oxidation state
(1) decreases as it gains electrons
(2) decreases as it loses electrons
(3) increases as it gains electrons
(4) increases as it loses electrons
5. The chemical process in which electrons are gained by an atom or ion is called
(1) addition
(2) oxidation
(3) reduction
(4) substitution
6. What occurs during the reaction: 4 HCl + MnO2  MnCl2 + 2 H2O + Cl2 ?
(1) The manganese is reduced and its oxidation number changes from +4 to +2
(2) The manganese is oxidized and its oxidation number changes from +4 to +2
(3) The manganese is reduced and its oxidation number changes from +2 to +4
(4) The manganese is oxidized and its oxidation number changes from +2 to +4
7. Which balanced equation represents a redox reaction?
(1) Mg + Cl2  MgCl2
(2) CaO + H2O  Ca(OH)2
(3) HNO3 + NaOH  NaNO3 + H2O
(4) NaCl + AgNO3  AgCl + NaNO3
8. In a redox reaction, the substance reduced
(1) gains electrons and is the oxidizing agent
(2) gains electrons and is the reducing agent
(3) loses electrons and is the oxidizing agent
(4) loses electrons and is the reducing agent
9. Which half reaction equation represents the reduction of an iron (II) ion?
(1) Fe+2  Fe+3 + e(2) Fe+2 + 2 e-  Fe
(3) Fe+3 + e-  Fe+2
(4) Fe  Fe+2 + 2 e10. Given the reaction: Zn (s) + 2 HCl (aq)  ZnCl2 (aq) + H2 (g), which equation represents
the correct oxidation half reaction?
(1) Zn  Zn+2 + 2 e(2) 2 H+ + 2 e-  H2
+2
(3) Zn + 2 e  Zn
(4) 2 Cl-  Cl2 + 2 e-
11. In a redox reaction, how does the total number of electrons lost compare to the total
number of electrons gained?
(1) The number lost is always greater than the number gained
(2) The number lost is always equal to the number gained
(3) The number lost is sometimes equal to the number gained
(4) The number lost is sometimes less than the number gained
12. According to Table J, which of these ions is most easily reduced?
(1) Ca+2
(2) Cr+3
(3) Cu+
(4) Ag+
13. Which reaction will take place spontaneously?
(1) Ni+2 + Pb  Ni + Pb+2
(2) Au+3 + Al  Au + Al+3
(3) Sr+2 + Sn  Sr + Sn+2
(4) Fe+2 + Cu  Fe + Cu+2
14. Which process occurs in an operating voltaic cell?
(1) Electrical energy is converted to chemical energy
(2) Chemical energy is converted to electrical energy
(3) Oxidation takes place at the cathode
(4) Reduction takes place at the anode
15. In an operating voltaic cell, reduction occurs
(1) at the anode
(2) at the cathode
(3) in the salt bridge
(4) in the wire
16. Which process occurs at the anode in an electrochemical cell?
(1) the loss of protons
(2) the loss of electrons
(3) the gain of protons
(4) the gain of electrons
17. The diagram below represents an operating electrochemical cell and the balanced
equation for the reaction occurring in the cell.
Which statement identifies the part of the cell that conducts electrons and describes the
direction of electron flow as the cell operates?
(1) Electrons flow through the salt bridge from the Ni (s) to the Zn (s)
(2) Electrons flow through the salt bridge from the Zn (s) to the Ni (s)
(3) Electrons flow through the wire from the Ni (s) to the Zn (s)
(4) Electrons flow through the wire from the Zn (s) to the Ni (s)
18. At which electrode does oxidation occur in a voltaic cell and in an electrolytic cell?
(1) the anode in a voltaic cell and the cathode in an electrolytic cell
(2) the cathode in a voltaic cell and the anode in an electrolytic cell
(3) the anode in both a voltaic cell and an electrolytic cell
(4) the cathode in both a voltaic cell and an electrolytic cell
19. Given the balanced equation representing a reaction occurring in an electrolytic cell:
2 NaCl ()  2 Na () + Cl2 (g), where is Na () produced in the cell?
(1) at the anode, where oxidation occurs
(3) at the cathode, where oxidation occurs
(2) at the anode, where reduction occurs
(4) at the cathode, where reduction occurs
20. Given the diagram representing an incomplete electrochemical cell:
Solid copper will be deposited on one of the carbon electrodes when the wires are
connected to
(1) each other
(2) a battery
(3) a switch
(4) a voltmeter
21. Energy is required to produce a chemical change during
(1) chromatography
(2) electrolysis
(3) boiling
(4) melting