Question

In the reaction ${{H}_{2}}{{O}_{2}}+N{{a}_{2}}C{{O}_{3}}\to N{{a}_{2}}{{O}_{2}}+C{{O}_{2}}+{{H}_{2}}O$, the substance that is undergoing oxidation is:
A.${{H}_{2}}{{O}_{2}}$
B.$N{{a}_{2}}C{{O}_{3}}$
C.$N{{a}_{2}}{{O}_{3}}$
D. none of these

Answer 1

In order to find the substance which is oxidised, we need to check the change in oxidation number for the elements from the reactant side to the product side.

Complete step-by-step answer: In order to answer the question, we need to learn about oxidation and reduction. Now, a substance is said to be oxidised if hydrogen gets removed from it, or if oxygen gets added in it. On the other hand, in reduction, removal of oxygen or addition of hydrogen (any one) takes place. Oxidation number helps us in identifying the oxidation state of an atom. Oxidation number can be 0, negative and positive. If, in a reaction, the oxidation number increases in the product side, then we say that the particular element gets oxidised, and in case of reduction, the oxidation number gets reduced.
In a redox reaction, oxidation as well as reduction of an element occur simultaneously.
Now, let us come to the question. In the reaction, we can see that ${{H}_{2}}{{O}_{2}}$ is -1, $N{{a}_{2}}C{{O}_{3}}$ is -2, $N{{a}_{2}}{{O}_{2}}$ is -1, and $C{{O}_{2}}$ and ${{H}_{2}}O$ both are -2. If there was any change in the oxidation number in any element, then we would have concluded, or come to know, which element was oxidised or reduced. However, we can see that the oxidation number of each and every element has not changed. Since there is no such change of the oxidation number, we can say that the correct answer for this question will be option D ( none of these ).

Note: If oxidation number is negative or 0 it does not mean that the element is reduced. For example, if an atom changes its oxidation state from -1 to 0, then also it is said to be oxidised.