Class 11 Chemistry MCQ Chapter 8 Redox Reactions
Looking for Class 11 Chemistry MCQ Chapter 8 Redox Reactions English Medium? You are in the right place. This article provides a carefully selected collection of multiple-choice questions (MCQs) with answers to help AHSEC Higher Secondary First Year students prepare effectively for examinations.
The chapter Redox Reactions explains the transfer of electrons during chemical reactions and the changes in oxidation states of elements. Students will learn about oxidation, reduction, oxidizing agents, reducing agents, oxidation number, balancing redox equations, and the importance of redox reactions in daily life and industrial processes. These concepts are fundamental to understanding many chemical reactions.
The MCQs included in this article are based on the latest AHSEC syllabus and exam pattern. They are designed to help students revise important topics, improve conceptual clarity, and practice objective questions that are commonly asked in examinations.
Whether you are studying for class tests, annual examinations, or the AHSEC HS First Year Final Examination, these MCQ solutions will help you strengthen your Chemistry preparation and score higher marks.
Part II
Class 11 Chemistry MCQ Chapter 8 Redox Reactions
Selected VSA & MCQ
I. Very Short Answer Questions (VSA)
Q: What is oxidation in terms of electron transfer?
Ans: Oxidation is the process in which a substance loses one or more electrons.
Q: What is reduction in terms of electron transfer?
Ans: Reduction is the process in which a substance gains one or more electrons.
Q: What is a redox reaction?
Ans: A redox reaction is a chemical reaction in which oxidation and reduction occur simultaneously.
Q: What is an oxidising agent?
Ans: An oxidising agent is a substance that oxidises another substance and itself gets reduced.
Q: What is a reducing agent?
Ans: A reducing agent is a substance that reduces another substance and itself gets oxidised.
Q: Define oxidation number.
Ans: Oxidation number is the apparent charge assigned to an atom in a compound or ion according to certain rules.
Q: What is the oxidation number of an element in its free state?
Ans: The oxidation number of an element in its free state is zero.
Q: What is the oxidation number of oxygen in most compounds?
Ans: The oxidation number of oxygen in most compounds is –2.
Q: What is the oxidation number of hydrogen in most compounds?
Ans: The oxidation number of hydrogen in most compounds is +1.
Q: What is a disproportionation reaction?
Ans: A disproportionation reaction is a redox reaction in which the same substance undergoes both oxidation and reduction.
Q: What is the oxidation number of sodium in NaCl?
Ans: The oxidation number of sodium in NaCl is +1.
Q: What is the oxidation number of chlorine in NaCl?
Ans: The oxidation number of chlorine in NaCl is –1.
Q: Why are redox reactions important in daily life?
Ans: Redox reactions are important because they are involved in respiration, combustion, corrosion, bleaching and many industrial processes.
Q: What is corrosion?
Ans: Corrosion is the gradual destruction of metals due to chemical reactions with the environment.
Q: What is rancidity?
Ans: Rancidity is the oxidation of fats and oils in food, causing unpleasant smell and taste.
Q: What is the oxidation number of fluorine in its compounds?
Ans: The oxidation number of fluorine in its compounds is always –1.
Q: What is the sum of oxidation numbers in a neutral compound?
Ans: The sum of oxidation numbers of all atoms in a neutral compound is zero.
Q: What is the sum of oxidation numbers in a polyatomic ion?
Ans: The sum of oxidation numbers of all atoms in a polyatomic ion is equal to the charge on the ion.
Q: What is meant by oxidation in terms of oxygen?
Ans: Oxidation is the addition of oxygen to a substance.
Q: What is meant by reduction in terms of hydrogen?
Ans: Reduction is the addition of hydrogen to a substance.
Q: Why is redox reaction called an electron transfer reaction?
Ans: Redox reaction is called an electron transfer reaction because electrons are transferred from one substance to another during the reaction.
Q: What is bleaching action due to?
Ans: Bleaching action is due to oxidation process.
Q: State one use of potassium permanganate in redox reactions.
Ans: Potassium permanganate is used as a strong oxidising agent in chemical reactions.
Q: What is respiration in terms of redox reaction?
Ans: Respiration is a redox process in which glucose is oxidised to release energy.
Q: What happens to oxidation number during oxidation?
Ans: The oxidation number increases during oxidation.
Q: What happens to oxidation number during reduction?
Ans: The oxidation number decreases during reduction.
II. Multiple Choice Questions (MCQs)
Q: Oxidation is a process involving —
(a) Gain of electrons
(b) Loss of electrons
(c) Gain of neutrons
(d) Loss of protons
Ans: (b) Loss of electrons
Q: Reduction involves —
(a) Loss of electrons
(b) Gain of electrons
(c) Loss of atoms
(d) Gain of oxygen
Ans: (b) Gain of electrons
Q: In a redox reaction, oxidation and reduction occur —
(a) Separately
(b) Simultaneously
(c) Alternately
(d) Slowly
Ans: (b) Simultaneously
Q: The oxidation number of an element in free state is —
(a) +1
(b) –1
(c) 0
(d) +2
Ans: (c) 0
Q: The oxidation number of oxygen in most compounds is —
(a) +2
(b) –2
(c) +1
(d) –1
Ans: (b) –2
Q: The oxidation number of hydrogen in most compounds is —
(a) –1
(b) –2
(c) +1
(d) +2
Ans: (c) +1
Q: Which of the following acts as an oxidising agent?
(a) Substance gaining electrons
(b) Substance losing electrons
(c) Substance gaining protons
(d) Substance losing neutrons
Ans: (a) Substance gaining electrons
Q: Which of the following acts as a reducing agent?
(a) Substance getting reduced
(b) Substance gaining electrons
(c) Substance getting oxidised
(d) Substance gaining oxygen
Ans: (c) Substance getting oxidised
Q: The oxidation number of sodium in NaCl is —
(a) –1
(b) +1
(c) +2
(d) 0
Ans: (b) +1
Q: The oxidation number of chlorine in NaCl is —
(a) +1
(b) –1
(c) 0
(d) +2
Ans: (b) –1
Q: The sum of oxidation numbers in a neutral compound is —
(a) +1
(b) –1
(c) Zero
(d) Variable
Ans: (c) Zero
Q: The sum of oxidation numbers in a polyatomic ion is equal to —
(a) Number of atoms
(b) Charge on the ion
(c) Number of electrons
(d) Number of neutrons
Ans: (b) Charge on the ion
Q: The oxidation number of sulphur in (H_2SO_4) is —
(a) +4
(b) +2
(c) +6
(d) –2
Ans: (c) +6
Q: The oxidation number of nitrogen in (NH_3) is —
(a) +3
(b) –3
(c) +5
(d) –5
Ans: (b) –3
Q: Which process involves the addition of oxygen?
(a) Reduction
(b) Neutralisation
(c) Oxidation
(d) Hydrolysis
Ans: (c) Oxidation
Q: Which process involves the addition of hydrogen?
(a) Oxidation
(b) Reduction
(c) Ionisation
(d) Sublimation
Ans: (b) Reduction
Q: Corrosion of iron is commonly known as —
(a) Crystallisation
(b) Rusting
(c) Sublimation
(d) Distillation
Ans: (b) Rusting
Q: Rancidity occurs due to —
(a) Reduction of oils
(b) Oxidation of oils and fats
(c) Hydrolysis of salts
(d) Neutralisation
Ans: (b) Oxidation of oils and fats
Q: Which element always shows oxidation number –1 in its compounds?
(a) Oxygen
(b) Chlorine
(c) Fluorine
(d) Hydrogen
Ans: (c) Fluorine
Q: Potassium permanganate is generally used as —
(a) Reducing agent
(b) Catalyst
(c) Oxidising agent
(d) Acid
Ans: (c) Oxidising agent
Q: In respiration, glucose undergoes —
(a) Reduction
(b) Oxidation
(c) Neutralisation
(d) Precipitation
Ans: (b) Oxidation
Q: During oxidation, oxidation number —
(a) Decreases
(b) Remains same
(c) Increases
(d) Becomes zero
Ans: (c) Increases
Q: During reduction, oxidation number —
(a) Increases
(b) Decreases
(c) Remains constant
(d) Becomes positive
Ans: (b) Decreases
Q: Assertion (A): Oxidation involves loss of electrons.
Reason (R): Reduction involves gain of electrons.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Ans: (b) Both A and R are true but R is not the correct explanation of A
Q: Assertion (A): Oxidising agents themselves get reduced.
Reason (R): Oxidising agents accept electrons from other substances.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Ans: (a) Both A and R are true and R is the correct explanation of A
Q: Assertion (A): The oxidation number of oxygen in most compounds is –2.
Reason (R): Oxygen is highly electronegative.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Ans: (a) Both A and R are true and R is the correct explanation of A
Q: Assertion (A): In a redox reaction, oxidation and reduction occur together.
Reason (R): Electrons lost by one substance are gained by another substance.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Ans: (a) Both A and R are true and R is the correct explanation of A
Q: Assertion (A): Fluorine always shows oxidation number –1 in its compounds.
Reason (R): Fluorine is the most electronegative element.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Ans: (a) Both A and R are true and R is the correct explanation of A
Q: Assertion (A): Corrosion is a redox process.
Reason (R): Corrosion involves the oxidation of metals.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Ans: (a) Both A and R are true and R is the correct explanation of A
Q: Assertion (A): The oxidation number of hydrogen in NaH is +1.
Reason (R): Hydrogen shows –1 oxidation number in metal hydrides.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is not the correct explanation of A
(c) A is true but R is false
(d) A is false but R is true
Ans: (d) A is false but R is true.
