Question

Which one of the following is an amphoteric oxide?
A)$N{{a}_{2}}O$
B)$S{{O}_{2}}$
C)${{B}_{2}}{{O}_{3}}$
D)$ZnO$

Answer 1

Hint: The answer for this question includes the definition of amphoteric oxides that is nothing but the species that can react with acids as well as bases and mostly the metallic oxides fall under this category and this fact helps you to approach the correct answer.

Complete answer:
We have come across various terms regarding the description of types of the compounds we make use of and also based on how they react.
Now, let us focus on what actually amphoteric oxide mean and which all substances come under this category.
- The definition of amphoteric oxides says that they can react with both acids as well as bases.
-Usually this reaction is the one where the oxide reacts with either acid or base to produce salt and water.
- Usually the amphoteric oxides are the metallic oxides and they react with both acids and bases.
- Based on these above facts we can say that from the options A), B) and C) all the oxides that are given are non metallic even if some of them are having metallic centre.
Thus, zinc oxide react with both acid and base and the reaction is as shown below,
With acid:$ZnO+{{H}_{2}}S{{O}_{4}}\to ZnS{{O}_{4}}+{{H}_{2}}O$
With base:$ZnO+2NaOH\to N{{a}_{2}}[Zn{{(OH)}_{4}}]$
Thus, the reaction of zinc oxide with acid produces salt and water and that with base forms sodium zincate.

Therefore, the correct answer is option D) $ZnO$

Note: Note that the amphoterism depends on the oxidation state that is available to a chemical species and this is because metals have multiple oxidation states and they form the amphoteric oxides and also hydroxides.