In Class 11 Final Exams there will be Case studies and Passage Based Questions will be asked, So practice these types of questions. Study Rate is always there to help you. Free PDF Download of CBSE Class 11 Chemistry Chapter 8 Case Study and Passage Based Questions with Answers were Prepared Based on Latest Exam Pattern. Students can solve NCERT Class 11 Chemistry Redox Reactions to know their preparation level.

In CBSE Class 11 Chemistry Paper, There will be a few questions based on case studies and passage-based as well. In that, a paragraph will be given, and then the MCQ questions based on it will be asked.

Redox Reactions Case Study Questions With answers

Here, we have provided case-based/passage-based questions for Class 11 Chemistry Chapter 8 Redox Reactions

Case Study/Passage-Based Questions

Case Study 1:

The idea of oxidation number has been invariably applied to define oxidation, reduction, oxidising agent (oxidant), reducing agent (reductant) and the redox reaction. To summarise, we may say that:

Oxidation: An increase in the oxidation number of the element in the given substance.

Reduction: A decrease in the oxidation number of the element in the given substance.

Oxidising agent: A reagent which can increase the oxidation number of an element in a given substance. These reagents are called as oxidants also.

Reducing agent: A reagent which lowers the oxidation number of an element in a given substance. These reagents are also called as reductants.

Redox reactions: Reactions which involve change in oxidation number of the interacting species.

Types of Redox Reactions

1.) Combination reactions -A combination reaction may be denoted in the manner:

A + B → C

Either A and B or both A and B must be in the elemental form for such a reaction to be a redox reaction. All combustion reactions, which make use of elemental dioxygen, as well as other reactions involving elements other than dioxygen, are redox reactions. Some important examples of this category are:

2.) Decomposition reactions- Decomposition reactions are the opposite of combination reactions. Precisely, a decomposition reaction leads to the breakdown of a compound into two or more components at least one of which must be in the elemental state.

Examples of this class of reactions are:

It may carefully be noted that there is no change in the oxidation number of hydrogen in methane under combination reactions and that of potassium in potassium chlorate in reaction. This may also be noted here that all decomposition reactions are not redox reactions. For example, decomposition of calcium carbonate is not a redox reaction.

3.) Displacement reactions- In a displacement reaction, an ion (or an atom) in a compound is replaced by an ion (or an atom) of another element. It may be denoted as:

X + YZ → XZ + Y

Displacement reactions fit into two categories: metal displacement and non-metal displacement.

(a) Metal displacement: A metal in a compound can be displaced by another metal in the uncombined state. Metal displacement reactions find many applications in metallurgical processes in which pure metals are obtained from their compounds in ores.

(b) Non-metal displacement: The non-metal displacement redox reactions include hydrogen displacement and a rarely occurring reaction involving oxygen displacement. All alkali metals and some alkaline earth metals (Ca, Sr, and Ba) which are very good reductants, will displace hydrogen from cold water. Many metals, including those which do not react with cold water, are capable of displacing hydrogen from acids. Dihydrogen from acids may even be produced by such metals which do not react with steam. Cadmium and tin are the examples of such metals.

4.) Disproportionation reactions – Disproportionation reactions are a special type of redox reactions. In a disproportionation reaction an element in one oxidation state is simultaneously oxidised and reduced. One of the reacting substances in a disproportionation reaction always contains an element that can exist in at least three oxidation states. The element in the form of reacting substance is in the intermediate oxidation state; and both higher and lower oxidation states of that element are formed in the reaction. The decomposition of hydrogen peroxide is a familiar example of the reaction, where oxygen experiences disproportionation.

Here the oxygen of peroxide, which is present in –1 state, is converted to zero oxidation state in O2 and decreases to –2 oxidation state in H2O.

[A] MCQ

1) In … an ion (or an atom) in a compound is replaced by an ion (or an atom) of another element.

• a) displacement reaction
• b) decomposition reaction
• c) disproportionation reaction
• d) combination reaction

Ans- a) displacement reaction

2) … leads to the breakdown of a compound into two or more components at least one of which must be in the elemental state.

• a) displacement reaction
• b) decomposition reaction
• c) disproportionation reaction
• d) combination reaction

Ans- b) decomposition reaction

3) In …. an element in one oxidation state is simultaneously oxidised and reduced.

• a) displacement reaction
• b) decomposition reaction
• c) disproportionation reaction
• d) combination reaction

Ans- c) disproportionation reaction

4) Reactions which involve change in oxidation number of the interacting species…

• a) Exothermic reaction
• b) Endothermic reaction
• c) Neutralization reaction
• d) Redox reaction

Ans- d) Redox reaction

5) One of the reacting substances in a disproportionation reaction always contains an element that can exist in at least … oxidation states.

• a) 1
• b) 2
• c) 3
• d) 4

Ans- c) 3

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