Question 6 - MCQs from NCERT Exemplar - Chapter 1 Class 10 - Chemical Reactions and Equations

A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears.

Which of the following is the correct explanation for the observation?

(A) KMnO ₄ is an oxidising agent, it oxidises FeSO ₄

(B) FeSO ₄ acts as an oxidising agent and it oxidizes KMnO ₄

(C) The colour disappears due to dilution; no reaction is involved

(D) KMnO ₄ is an unstable compound and decomposes in presence of FeSO ₄ to a colourless compound.

Answer

The reaction taking place in the beaker is as follows:

Now,

• Addition of oxygen is known as oxidation 
• Removal of oxygen is known as reduction.

Also,

• The substance which oxidises the other substances in a chemical reaction is known as an oxidising agent.  
• Likewise, the substance which reduces the other substance in a chemical reaction is known as a reducing agent.

It is known that KMnO ₄ is an oxidizing agent . And therefore, it oxidises FeSO ₄ to Fe ₂ (SO ₄ ) ₃

Also, KMnO ₄ is colored purple. Since in the reaction,  KMnO ₄ eventually becomes K ₂ SO ₄ … the purple color fades

So, the correct option is (a) KMnO ₄ is an oxidising agent, it oxidises FeSO ₄