Chemistry Class-11: Chapter – 8. Redox Reactions Part – 3 (For CBSE, ICSE, IAS, NET, NRA 2022)

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III. Short Answer Type

Question: 17

The reaction

Represents the process of bleaching. Identify and name the species that bleaches the substances due to its oxidising action.


Hypochlorite ion

Question: 18

undergoes disproportionation reaction in acidic medium but does not. Give reason.


In is in the highest oxidation state i.e.. . Therefore, it does not undergo disproportionation. undergoes disproportionation as follows:

Question: 19

and react with according to following chemical equations:

Why do these compounds differ in their reactivity?


(Hint: Note the oxidation number of lead in the oxides)

Question: 20

Nitric acid is an oxidising agent and reacts with but it does not react with . Explain why?


is a basic oxide and simple acid base reaction takes place between and . On the other hand in lead is in oxidation state and cannot be oxidised further. Therefore no reaction takes place. Thus, is passive, only reacts with .

Question: 21

Write balanced chemical equation for the following reactions:

(i) Permanganate ion reacts with sulphur dioxide gas in acidic medium to produce and hydrogen sulphate ion.

(Balance by ion electron method)

(ii) Reaction of liquid hydrazine with chlorate ion in basic medium produces nitric oxide gas and chloride ion in gaseous state.

(Balance by oxidation number method)

(iii) Dichlorine heptaoxide in gaseous state combines with an aqueous solution of hydrogen peroxide in acidic medium to give chlorite ion and oxygen gas.

(Balance by ion electron method)


Question: 22

Calculate the oxidation number of phosphorus in the following species.




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