Take timed practice tests on General Organic Chemistry for JEE Main and JEE Advanced with session-wise drills, score review, and explanation-led revision.
Six 20-question timed sessions plus a 60-question chapter module. Each item is original and reframed for copyright safety.
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1. In ethene (CH₂=CH₂), the hybridisation of carbon is:
Explanation: In alkenes, the double-bond carbon is sp² hybridised (3 sigma bonds + 1 pi bond). Bond angles ≈ 120°.
2. The inductive effect of −OH group relative to −H is:
Explanation: The −OH group is electron-withdrawing via inductive effect (O is more electronegative than C). However, it is electron-donating via resonance (+M effect) in aromatic systems.
3. The functional group present in carboxylic acids is:
Explanation: Carboxylic acids contain the −COOH (carboxyl) functional group. −CHO = aldehyde, −OH = alcohol, −CO− = ketone.
4. Successive members of a homologous series differ by:
Explanation: A homologous series consists of compounds with same functional group differing by −CH₂− (methylene) units. Molecular formula increases by CH₂ (14 mass units) between successive members.
5. The resonance structures of benzene are equivalent because:
Explanation: Benzene has 6 delocalized pi electrons over the ring, making all C−C bond lengths equal (1.40 Å, intermediate between single 1.54 Å and double 1.34 Å). Resonance is not physical switching between structures.
6. The −NH₂ group shows +M effect because:
Explanation: +M effect: lone pair of electrons on N is donated into the adjacent pi system via resonance. This increases electron density in the ring and makes −NH₂ an ortho-para director and ring activator.
7. The stability order of carbocations is:
Explanation: Stability order due to hyperconjugation and inductive effect: tertiary (3°) > secondary (2°) > primary (1°) > methyl (CH₃⁺). More alkyl groups = more hyperconjugation = more stable.
8. Carbanion stability order is:
Explanation: Carbanions (negatively charged carbon) are destabilised by electron-donating alkyl groups. More alkyl groups = less stable carbanion. So: tertiary
9. Acidity of alcohols follows the order:
Explanation: Wait — the actual order of acidity is CH₃OH > C₂H₅OH > (CH₃)₂CHOH > (CH₃)₃COH. More alkyl groups = more electron donation = less stable alkoxide ion = less acidic. So methanol is most acidic alcohol (among simple alcohols), tert-butanol is least acidic.
10. The reaction of CH₃Br with NaOH(aq) predominantly gives:
Explanation: Primary alkyl halides with aqueous NaOH preferentially undergo SN2 substitution to give alcohol. Elimination is favoured with alcoholic NaOH and heat.
11. Among the following, which compound shows the highest acidity?
Explanation: Electron-withdrawing groups stabilise the carboxylate anion, increasing acidity. F is more electronegative than Cl, so CF₃COOH has stronger −I effect than CCl₃COOH. pKa: CF₃COOH (0.23)
12. In polar aprotic solvents (e.g., DMSO), the nucleophilicity order of halide ions is:
Explanation: In polar aprotic solvents (no H-bonding to nucleophile), nucleophilicity parallels polarizability: I⁻ > Br⁻ > Cl⁻ > F⁻. In polar protic solvents, F⁻ is the most solvated and hence least nucleophilic; order reverses. In aprotic solvents, solvation is less — inherent nucleophilicity determines order.
13. Phenol is more acidic than cyclohexanol because:
Explanation: Phenoxide ion (C₆H₅O⁻) is resonance-stabilised: the negative charge delocalises over the ring through 4 resonance structures. Cyclohexoxide has no such delocalisation. Greater anion stability → higher acidity of phenol.
14. The stability of free radicals follows the order:
Explanation: Free radical stability parallels carbocation stability due to hyperconjugation: tertiary > secondary > primary > methyl. Additionally, allylic and benzylic radicals are more stable than even tertiary due to resonance.
15. The IUPAC name of CH₃−CH(OH)−CH₃ is:
Explanation: 3-carbon chain with OH on C2: propan-2-ol. (Isopropyl alcohol is the common name.)
16. An electrophile is a species that:
Explanation: An electrophile (electron lover) accepts an electron pair from a nucleophile. It can be positively charged (like H⁺, NO₂⁺) or neutral but electron-deficient (like BF₃, AlCl₃).
17. Among CH₃CH₂OH, CH₃COOH, HCOOH, and PhOH, the most acidic is:
Explanation: pKa values: HCOOH (3.75)