Organic conversions in JEE rely on a set of named reactions and reagents that you must know cold. This set covers preparation and reactions of hydrocarbons, alcohols, aldehydes and ketones: Wurtz, Kolbe, ozonolysis, hydroboration, Grignard, aldol, Cannizzaro, Rosenmund, Clemmensen and the standard laboratory tests.
How to practise: read each question and tap the option you think is correct. You will see right away whether you got it, along with a short explanation, and your score is tracked at the bottom of the screen. This set has 15 questions.
Topics covered in this set
- Wurtz, Kolbe and ozonolysis
- Hydroboration and aromaticity
- Grignard reagents and alcohol synthesis
- Oxidation and reduction reagents
- Aldol and Cannizzaro reactions
- Lucas, iodoform and Tollens tests
JEE Chemistry MCQs with answers and explanations
Q1. What is the main product when methyl bromide is treated with sodium in dry ether?
a) Propane
b) Methane
c) Ethene
d) Ethane
Q2. Electrolysis of aqueous sodium ethanoate (Kolbe's method) gives which hydrocarbon at the anode?
a) Butane
b) Methane
c) Propane
d) Ethane
Q3. What is formed by ozonolysis of but-2-ene followed by Zn/H₂O?
a) Propanal and methanal
b) Two molecules of propanone
c) Two molecules of ethanal
d) Butanal
Q4. What is the main product of hydroboration–oxidation (B₂H₆, then H₂O₂/OH⁻) of propene?
a) Propane-1,2-diol
b) Propanal
c) Propan-2-ol
d) Propan-1-ol
Q5. Which species is aromatic?
a) Cyclooctatetraene (planar)
b) Cyclobutadiene
c) Cyclopentadienyl anion
d) Cyclopentadienyl cation
Q6. A Grignard reagent RMgX reacts with methanal (HCHO), followed by hydrolysis. Which type of alcohol is formed?
a) Methanol
b) Secondary
c) Tertiary
d) Primary
Q7. Which alcohol gives turbidity immediately with the Lucas reagent (conc. HCl + anhydrous ZnCl₂) at room temperature?
a) Ethanol
b) Butan-2-ol
c) Propan-1-ol
d) 2-Methylpropan-2-ol
Q8. Which reagent oxidises a primary alcohol to an aldehyde without further oxidation to a carboxylic acid?
a) PCC (pyridinium chlorochromate)
b) Acidified K₂Cr₂O₇ in excess
c) Acidified KMnO₄
d) Conc. HNO₃
Q9. Benzoyl chloride is converted to benzaldehyde by H₂ over Pd/BaSO₄. This reaction is called:
a) Stephen reduction
b) Clemmensen reduction
c) Rosenmund reduction
d) Etard reaction
Q10. Which reagent converts a ketone C=O group directly into a CH₂ group under acidic conditions?
a) LiAlH₄
b) NaBH₄
c) H₂NNH₂ / KOH in ethylene glycol
d) Zn–Hg / conc. HCl
Q11. What is the product when ethanal is treated with dilute NaOH?
a) But-2-enoic acid
b) Ethane
c) Ethanol and sodium ethanoate
d) 3-Hydroxybutanal
Q12. Which compound undergoes the Cannizzaro reaction with concentrated NaOH?
a) Ethanal
b) Propanal
c) Methanal
d) Propanone
Q13. Which compound gives a positive iodoform test (yellow precipitate with I₂/NaOH)?
a) Propan-2-ol
b) Methanol
c) Propan-1-ol
d) Pentan-3-one
Q14. Which compound gives a silver mirror with Tollens' reagent?
a) Propanone
b) Propan-2-ol
c) Propanal
d) Propanoic acid
Q15. What is the major product when benzene reacts with CH₃COCl in the presence of anhydrous AlCl₃?
a) Benzoic acid
b) Toluene
c) Acetophenone
d) Benzaldehyde
Quick revision notes
- Wurtz doubles the alkyl group; Kolbe electrolysis of RCOONa gives R–R.
- Hydroboration–oxidation: anti-Markovnikov alcohol, no rearrangement.
- Grignard: HCHO → 1°, RCHO → 2°, ketone → 3° alcohol.
- Aldol needs α-H; Cannizzaro needs no α-H (HCHO, C₆H₅CHO).
- Iodoform: CH₃CO– or CH₃CH(OH)–; Tollens: aldehydes; Lucas: 3° reacts fastest.
Frequently asked questions
Are these JEE previous year questions?
No, they are original practice questions written to the NCERT-based JEE Main syllabus and level.
Why does ethanol give the iodoform test but methanol does not?
Ethanol is oxidised by I₂/NaOH to ethanal, which has a CH₃CO– group. Methanol only gives methanal, which lacks the methyl group next to the carbonyl.
How do I tell Clemmensen and Wolff–Kishner apart?
Both turn C=O into CH₂. Clemmensen uses acid (Zn–Hg, HCl) and Wolff–Kishner uses base (hydrazine, KOH), so choose based on which groups in the molecule are sensitive to acid or base.
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