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Class 11 Redox Reactions worksheet
CBSE Chemistry. Oxidation numbers, oxidising and reducing agents, balancing by half reactions, electrode potentials. Every sheet has 20 questions in three sections and an answer key, and the numbers change every time.
Sample questions
Real questions from this chapter, as the app sets them. Tap Answer to see the answer and working.
Section A · multiple choice
- 1.
In terms of electrons, oxidation is the:
- gain of protons
- loss of neutrons
- gain of electrons
- loss of electrons
Answer
(d) loss of electrons
- 2.
The oxidation number of iron in Fe₃O₄ is:
- +8/3
- −8/3
- +11/3
- +5/3
Answer
(a) +8/3
the oxidation numbers add up to the charge on the species
- 3.
In the reaction 2CuO + C → 2Cu + CO₂, the reducing agent is:
- CuO
- Cu
- C
- CO₂
Answer
(c) C
C is oxidised: C 0 → +4
Section B · short answer
- 4.
Define oxidation and reduction in terms of oxidation number.
Answer
Oxidation is an increase in the oxidation number of an element; reduction is a decrease.
- 5.
Find the oxidation number of each element in NO₃⁻.
Answer
N +5, O −2
the sum is the charge, −1
Section C · long answer
- 6.
Write the rules for finding the oxidation number of an element in a compound or ion.
Answer
An element in the free state has 0. A monatomic ion has its charge. Oxygen is −2 (−1 in peroxides, +2 in OF₂). Hydrogen is +1 (−1 in metal hydrides). Fluorine is always −1; alkali metals +1; alkaline earth metals +2. The sum of oxidation numbers is zero for a neutral compound and equals the charge for an ion.
Fresh sheets for your child
In the app, every Redox Reactions sheet is new: the app remembers the questions your child has already had and leaves them out. Print the sheet as a PDF, or use notebook mode and write the answers in a notebook.
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