Chapter Exam

Chapter 7: Redox Reactions — Online MCQ Test

Q: Which of the following best defines oxidation in terms of electron transfer?

Answer: B. Loss of electrons — Oxidation is defined as the loss of electrons. In redox reactions, the species that loses electrons is oxidized.

Q: Which species acts as a reducing agent in a redox reaction?

Answer: B. Species that loses electrons — A reducing agent donates electrons to another species and itself gets oxidized. Hence, it loses electrons.

Q: In the reaction CuO + H2 → Cu + H2O, which species is oxidised?

Answer: C. H2 — Hydrogen changes from oxidation number 0 in H2 to +1 in H2O, so it is oxidized. CuO is reduced to Cu.

Q: Which of the following represents the correct oxidation number change in the reaction 2FeCl2 + Cl2 → 2FeCl3?

Answer: A. Fe: +2 to +3; Cl: 0 to -1 — Iron is oxidized from +2 to +3, while chlorine is reduced from 0 in Cl2 to -1 in FeCl3. This is a redox reaction.

Q: Which one of the following is the correct balanced equation for the reaction of iron(II) with dichromate ion in acidic medium?

Answer: A. Cr2O7^2- + 6Fe2+ + 14H+ → 2Cr3+ + 6Fe3+ + 7H2O — Dichromate ion is reduced to Cr3+, and each Fe2+ is oxidized to Fe3+. The correct stoichiometric balance in acidic medium is Cr2O7^2- + 6Fe2+ + 14H+ → 2Cr3+ + 6Fe3+ + 7H2O.

CHEMISTRY · Grade 11 · CBSE(NCERT)

Practice Chapter 7: Redox Reactions with a free chapter-wise online MCQ test for CBSE(NCERT) Grade 11 CHEMISTRY. This chapter covers: Oxidation Reduction Oxidation number Reducing agent Oxidising agent Electron transfer Redox equation Balancing reactions Disproportionation. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 7: Redox Reactions — Important Questions & Answers (FAQ)

Frequently asked questions from CBSE(NCERT) Grade 11 CHEMISTRY — Chapter 7: Redox Reactions, with answers and explanations. These are sample questions; the exam has its own separate question set.

Which of the following best defines oxidation in terms of electron transfer?

A. Gain of electrons
B. Loss of electrons ✓
C. Gain of protons
D. Loss of neutrons

Answer: B. Loss of electrons
Oxidation is defined as the loss of electrons. In redox reactions, the species that loses electrons is oxidized.

Which species acts as a reducing agent in a redox reaction?

A. Species that gains electrons
B. Species that loses electrons ✓
C. Species that is not changed
D. Species that always has oxidation number zero

Answer: B. Species that loses electrons
A reducing agent donates electrons to another species and itself gets oxidized. Hence, it loses electrons.

In the reaction CuO + H2 → Cu + H2O, which species is oxidised?

A. CuO
B. Cu
C. H2 ✓
D. H2O

Answer: C. H2
Hydrogen changes from oxidation number 0 in H2 to +1 in H2O, so it is oxidized. CuO is reduced to Cu.

Which of the following represents the correct oxidation number change in the reaction 2FeCl2 + Cl2 → 2FeCl3?

A. Fe: +2 to +3; Cl: 0 to -1 ✓
B. Fe: +3 to +2; Cl: -1 to 0
C. Fe: 0 to +2; Cl: 0 to +1
D. Fe: +2 to 0; Cl: -1 to 0

Answer: A. Fe: +2 to +3; Cl: 0 to -1
Iron is oxidized from +2 to +3, while chlorine is reduced from 0 in Cl2 to -1 in FeCl3. This is a redox reaction.

Which one of the following is the correct balanced equation for the reaction of iron(II) with dichromate ion in acidic medium?

A. Cr2O7^2- + 6Fe2+ + 14H+ → 2Cr3+ + 6Fe3+ + 7H2O ✓
B. Cr2O7^2- + 3Fe2+ + 14H+ → 2Cr3+ + 3Fe3+ + 7H2O
C. Cr2O7^2- + 6Fe3+ + 14H+ → 2Cr3+ + 6Fe2+ + 7H2O
D. 2Cr2O7^2- + 6Fe2+ + 14H+ → 4Cr3+ + 6Fe3+ + 7H2O

Answer: A. Cr2O7^2- + 6Fe2+ + 14H+ → 2Cr3+ + 6Fe3+ + 7H2O
Dichromate ion is reduced to Cr3+, and each Fe2+ is oxidized to Fe3+. The correct stoichiometric balance in acidic medium is Cr2O7^2- + 6Fe2+ + 14H+ → 2Cr3+ + 6Fe3+ + 7H2O.

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