NEET Chemistry practice Questions– Set 2 (Organic Chemistry Basics)

 

NEET Chemistry  – Set 2 (Organic Chemistry Basics)

Organic Chemistry is like the grammar of molecules. In this set, you’ll solve 10 NEET-level questions from **GOC, Isomerism, Resonance, Hybridisation, Reaction Intermediates**—the backbone of Organic reasoning. Click on **Check Answer** to reveal step-by-step solutions (Hinglish + English for clarity).

Q11. Which of the following has the highest acidic strength?

Phenol Ethanol Water o-Nitrophenol

Correct: o-Nitrophenol

Explanation: The –NO₂ group withdraws electrons strongly → stabilises phenoxide ion → increases acidity. Phenol < o-nitrophenol is a classic order seen in NEET repeatedly.

Q12. Correct order of stability of carbocations:

\( \ce{(CH3)3C+,\ (CH3)2CH+,\ CH3CH2+, \ CH3+} \)

\( \ce{3^\circ > 2^\circ > 1^\circ > CH3+} \) \( \ce{1^\circ > 2^\circ > 3^\circ > CH3+} \) \( \ce{2^\circ > 3^\circ > 1^\circ > CH3+} \) All are equally stable

Correct: \( \ce{3^\circ > 2^\circ > 1^\circ > CH3+} \)

Explanation: Hyperconjugation + inductive effect → more alkyl groups stabilize carbocations strongly.

Q13. The correct resonance structures exist in:

\( \ce{CO3^{2-}} \) \( \ce{NH4+} \) \( \ce{CH4} \) \( \ce{H2O} \)

Correct: \( \ce{CO3^{2-}} \)

Explanation: Carbonate has delocalised π-electrons forming 3 equivalent resonance structures → classic inorganic-organic crossover.

Q14. Hybridisation of carbon in allene (\( \ce{CH2=C=CH2} \)) is:

\( \mathrm{sp^3,\ sp^3,\ sp^3} \) \( \mathrm{sp^2,\ sp^2,\ sp^2} \) \( \mathrm{sp,\ sp,\ sp} \) \( \mathrm{sp^2,\ sp,\ sp^2} \)

Correct: \( \mathrm{sp^2,\ sp,\ sp^2} \)

Explanation: Middle carbon is cumulative double-bond carbon → sp hybridised; terminal carbons are sp².

Q15. Which is the strongest base?

\( \ce{NH3} \) \( \ce{C6H5NH2} \) \( \ce{(CH3)NH2} \) \( \ce{(CH3)3N} \)

Correct: \( \ce{(CH3)NH2} \)

Explanation: More +I effect → higher electron density on N → stronger base. Aromatic amine is least basic due to resonance withdrawal.

Q16. Which among the following has geometrical isomerism?

\( \ce{CH3CH=CH2} \) \( \ce{CH3CH=CHCH3} \) \( \ce{CH2=CCl2} \) \( \ce{CCl2=CCl2} \)

Correct: \( \ce{CH3CH=CHCH3} \)

Explanation: Alkene needs different groups on each double-bonded carbon → only but-2-ene qualifies (cis/trans).

Q17. Which is aromatic?

Cyclooctatetraene Benzene Cyclobutadiene Cyclohexene

Correct: Benzene

Explanation: Planar + cyclic + fully conjugated + obeys \(4n+2\pi\) rule (n=1). Aromatic = ultra-stable.

Q18. Which of the following shows hyperconjugation?

\( \ce{CH3-CH3} \) \( \ce{CH3-CH=CH2} \) \( \ce{CH2=CH2} \) \( \ce{CH4} \)

Correct: \( \ce{CH3-CH=CH2} \)

Explanation: Alkene adjacent to alkyl group → hyperconjugative structures → stabilisation.

Q19. Which reagent gives Lucas Test fastest?

\( \ce{CH3OH} \) \( \ce{CH3CH2OH} \) \( \ce{(CH3)2CHOH} \) \( \ce{(CH3)3COH} \)

Correct: \( \ce{(CH3)3COH} \)

Explanation: Lucas test rate ∝ carbocation stability → tertiary alcohol reacts instantly.

Q20. Electrophile in nitration of benzene is:

\( \ce{NO2^-} \) \( \ce{NO2+} \) \( \ce{HNO3} \) \( \ce{H2SO4} \)

Correct: \( \ce{NO2+} \) (Nitronium ion)

Explanation: Generated from \( \ce{HNO3 + H2SO4} \), nitronium is the actual aromatic substitution electrophile.

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