Relevant Titles
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NCERT Quiz: Combustion, Pyrolysis & Oxidation — CBSE Class 11 Chemistry MCQs
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CBSE Class 11 Hydrocarbons MCQs: Combustion, Pyrolysis and Oxidation Practice Test
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Class 11 Chemistry Online Quiz — Combustion, Pyrolysis & Oxidation (NCERT)
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Master Combustion & Pyrolysis: CBSE Class 11 MCQs with Explanations
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CBSE Class 11 Chemistry — NCERT-Based MCQs on Oxidation Reactions
Introduction
Prepare effectively for your CBSE Class 11 board exams with this NCERT-aligned online quiz on Combustion, Pyrolysis, and Oxidation — core topics from Chapter 13: Hydrocarbons (Part C: Organic Chemistry). This targeted MCQ set reinforces essential ideas such as complete versus incomplete combustion (products like CO₂ and CO), thermal cracking during pyrolysis that yields smaller alkanes/alkenes and char, and stepwise oxidation of functional groups using reagents like KMnO₄ or PCC. Each question comes with an immediate explanation and correctly formatted chemical notations (for example, CO₂ and H₂O) to help you visualise reaction pathways and remember reagent-specific outcomes. Ideal for timed revision or focused self-assessment, the quiz helps identify weak areas, sharpen problem-solving skills, and boost confidence before exams. Because every item maps strictly to the NCERT syllabus, this resource is especially useful for CBSE Class 11 students aiming for clarity and board-level readiness. Attempt the quiz, review instant feedback, and strengthen your understanding of hydrocarbon combustion, pyrolysis, and oxidation reactions.
Sample MCQs (with Answers & Explanations)
Q1. Complete combustion of butane (C₄H₁₀) in excess oxygen yields:
A. CO + H₂O
B. CO₂ + H₂O
C. C (soot) + H₂O
D. CO₂ + H₂
Answer: B — CO₂ + H₂O
Explanation: In complete combustion (sufficient O₂), hydrocarbons oxidise fully to CO₂ and H₂O. Example: 2 C₄H₁₀ + 13 O₂ → 8 CO₂ + 10 H₂O.
Q2. Pyrolysis of long-chain hydrocarbons primarily produces:
A. Only carbon dioxide and water
B. Smaller alkanes and alkenes plus some char/tars
C. Pure alcohols
D. Nitrogen oxides
Answer: B — Smaller alkanes and alkenes plus some char/tars
Explanation: Pyrolysis is thermal decomposition in low/no O₂ that breaks C–C bonds forming lighter hydrocarbons, tars and char — basis for cracking and bio-oil.
Q3. Which oxidising agent is most suitable for converting a primary alcohol to an aldehyde without further oxidation to an acid?
A. Hot KMnO₄ (acidic)
B. PCC (pyridinium chlorochromate)
C. Concentrated HNO₃
D. NaBH₄
Answer: B — PCC
Explanation: PCC is a mild oxidant that stops at the aldehyde stage (RCH₂OH → RCHO) under anhydrous conditions; strong reagents like hot KMnO₄ would oxidise further to carboxylic acids.
Q4. Incomplete combustion of methane in limited oxygen can form which toxic gas?
A. CO₂
B. CO
C. H₂
D. O₃
Answer: B — CO (carbon monoxide)
Explanation: Insufficient oxygen leads to partial oxidation producing CO, a colourless, odourless and toxic gas (CH₄ + 1.5 O₂ → CO + 2 H₂O).
Q5. Which observation indicates oxidation of an organic compound with KMnO₄ in a qualitative test?
A. Bromine orange colour remains unchanged
B. KMnO₄ purple decolourises (often to brown MnO₂)
C. Immediate flame is produced
D. Solution becomes basic with no colour change
Answer: B — KMnO₄ purple decolourises
Explanation: KMnO₄ (purple) is reduced when it oxidises organic substrates; decolourization (and sometimes brown MnO₂ precipitate) signals oxidation.