MCAT General Chemistry Question 54: Answer and Explanation
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Question: 54
9. Aluminum metal can be used to remove tarnish from silver when the two solid metals are placed in water, according to the following reaction:
3 AgO + 2 Al → 3 Ag + Al2O3
This reaction is a:
I. double-displacement reaction.
II. single-displacement reaction.
III. oxidation–reduction reaction.
IV. combination reaction.
- A. II only
- B. IV only
- C. I and III only
- D. II and III only
Correct Answer: D
Explanation:
In the reaction, there is a single displacement, with the silver in silver oxide being replaced by the aluminum to form aluminum oxide. This single-displacement reaction also necessitates a transfer of electrons in an oxidation-reduction reaction; silver, for example, changes from the +2 oxidation state to neutral. Aluminum changes from neutral to the +3 oxidation state.