Question

In the following reactions, ${\rm{ZnO}}$ is respectively acting as a/an:
a. ${\rm{ZnO}} + {\rm{N}}{{\rm{a}}_{\rm{2}}}{\rm{O}} \to {\rm{N}}{{\rm{a}}_{\rm{2}}}{\rm{Zn}}{{\rm{O}}_{\rm{2}}}$
b. ${\rm{ZnO}} + {\rm{C}}{{\rm{O}}_{\rm{2}}} \to {\rm{ZnC}}{{\rm{O}}_{\rm{3}}}$
A. Base and base
B. Acid and acid
C. Acid and base
D. Base and acid

Answer 1

Hint: We know that, nature of oxides formed by different elements can be deduced from the position of the elements in the periodic table or the nature of the element itself.

Complete answer
Among other trends and properties of elements that can be deduced by using our modern periodic table, one of the important one is formula and nature of oxides. We have seen how helpful it was for the earlier scientists to as they used the same to classify and organize the elements accordingly.

Now, we know that in the modern periodic table, elements that are present on the left are metallic in nature and as we move towards right, metallic nature decreases. This gives us some metalloids in the middle and non-metals on the right excluding noble gases. Now, let’s talk about the nature of oxides. Metals on the left being highly electropositive give basic oxides and again this basicity decreases as the metallic nature. We have amphoteric oxides in the middle and acidic oxides from the non-metals.

Now let’s have a look at the oxides that we are dealing with. We are given oxides of zinc, sodium and carbon. From the above discussion, we can infer that sodium oxide is basic, zinc oxide is amphoteric and carbon dioxide is acidic in nature. So, while reacting with basic sodium oxide, zinc oxide must act as an acid and similarly, while reacting with acidic carbon dioxide, zinc oxide must act as a base.

Hence, the correct option is C. Acid and base

Note:
In the given reactions, there is no change in the oxidation state of any element; neither are we given acid and base with proton or hydroxide ions so as to distinguish on the basis of these. That is why we have simply used the nature of oxides.