Chapter-14 Organic Chemistry — Online MCQ Test
CHEMISTRY · Grade 10 · IGCSE cambridge
Practice Chapter-14 Organic Chemistry with a free chapter-wise online MCQ test.
This chapter covers: Alkanes alkenes alcohols and carboxylic acids fuels polymers and basic organic reactions..
AI-generated questions from basic to board-exam level, with instant results and explanations.
Chapter-14 Organic Chemistry — Important Questions & Answers
What is the general molecular formula for alkanes?
- A. CₙH₂ₙ
- B. CₙH₂ₙ₊₂
- C. CₙH₂ₙ₋₂
- D. CₙHₙ
Answer: B. CₙH₂ₙ₊₂
Alkanes are saturated hydrocarbons with only single bonds between carbon atoms, following the general formula CₙH₂ₙ₊₂.
Alkanes are saturated hydrocarbons with only single bonds between carbon atoms, following the general formula CₙH₂ₙ₊₂.
Which of the following is an alkene?
- A. Ethane (C₂H₆)
- B. Ethene (C₂H₄)
- C. Ethyne (C₂H₂)
- D. Ethanol (C₂H₆O)
Answer: B. Ethene (C₂H₄)
Ethene (C₂H₄) contains a carbon-carbon double bond (C=C), which is the characteristic feature of alkenes.
Ethene (C₂H₄) contains a carbon-carbon double bond (C=C), which is the characteristic feature of alkenes.
Why do alkenes decolorize bromine water while alkanes do not?
- A. Alkenes are more reactive due to the presence of C=C double bonds
- B. Alkanes have stronger bonds than alkenes
- C. Alkenes contain more hydrogen atoms
- D. Alkanes are insoluble in bromine water
Answer: A. Alkenes are more reactive due to the presence of C=C double bonds
The C=C double bond in alkenes is reactive and undergoes addition reaction with bromine, causing decolorization. Alkanes with only single bonds do not readily react with bromine.
The C=C double bond in alkenes is reactive and undergoes addition reaction with bromine, causing decolorization. Alkanes with only single bonds do not readily react with bromine.
A compound with molecular formula C₅H₁₂ reacts with bromine water but does not decolorize it. What can be concluded?
- A. The compound is an alkene
- B. The compound is an alkane
- C. The compound is an alcohol
- D. The compound is a carboxylic acid
Answer: B. The compound is an alkane
C₅H₁₂ fits the alkane formula CₙH₂ₙ₊₂. Since it does not decolorize bromine water, it lacks C=C double bonds and must be an alkane (pentane).
C₅H₁₂ fits the alkane formula CₙH₂ₙ₊₂. Since it does not decolorize bromine water, it lacks C=C double bonds and must be an alkane (pentane).
Which of the following compounds would produce a white precipitate when added to bromine water followed by addition of ammonia solution?
- A. Ethene
- B. Phenol
- C. Ethanol
- D. Methane
Answer: B. Phenol
Phenol reacts with bromine water to form a white precipitate of 2,4,6-tribromophenol. This is a characteristic test for phenols, not found in alkenes, alcohols, or alkanes.
Phenol reacts with bromine water to form a white precipitate of 2,4,6-tribromophenol. This is a characteristic test for phenols, not found in alkenes, alcohols, or alkanes.