ECAT — Engineering College Admission Test (UET)
Take the ECAT Chemistry — Organic Chemistry: Hydrocarbons to Carbonyls (Set 7): 30 multiple-choice questions (40 minutes) with instant scoring and a full…
What this test covers
The first 5 questions of this test, with the correct answer and explanation.
Q1. The IUPAC name of CH₃CH(CH₃)CH(CH₂CH₃)CH₂CH₃ is:
Answer: B. 3-ethyl-2-methylpentane
Explanation: The longest chain has 5 carbons (pentane). Numbering from the end nearer the first branch gives methyl at C-2 and ethyl at C-3; substituents are cited alphabetically: 3-ethyl-2-methylpentane.
Q2. How many structural isomers (ignoring cis–trans isomerism) are possible for the acyclic alkenes of molecular formula C₅H₁₀?
Answer: D. 5
Explanation: pent-1-ene, pent-2-ene, 2-methylbut-1-ene, 3-methylbut-1-ene and 2-methylbut-2-ene = 5.
Q3. The total number of stereoisomers (geometrical plus optical) of CH₃CH=CH–CHCl–CH₃ (4-chloropent-2-ene) is:
Answer: B. 4
Explanation: The C2=C3 double bond can be cis or trans, and C4 (H, Cl, CH₃, vinyl group) is a chiral centre with two enantiomeric forms. Total = 2 × 2 = 4.
Q4. The major product of the addition of HBr to 2-methylbut-2-ene in the absence of peroxides is:
Answer: C. 2-bromo-2-methylbutane
Explanation: By Markovnikov's rule H adds to the carbon bearing more H atoms, forming the more stable tertiary carbocation, then Br⁻ adds to the tertiary carbon.
Q5. Propene reacts with HCl in the presence of an organic peroxide. The major product is:
Answer: B. 2-chloropropane
Explanation: The peroxide (anti-Markovnikov) effect is observed only with HBr, so HCl adds by the ordinary Markovnikov route to give 2-chloropropane.
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Q6. Ozonolysis of 2-methylbut-2-ene, (CH₃)₂C=CHCH₃, followed by reductive work-up (Zn/H₂O), gives:
Q7. Cold, dilute, alkaline KMnO₄ (Baeyer's reagent) reacts with ethene to give mainly:
Q8. Which of the following gives a white precipitate with ammoniacal silver nitrate solution?
Q9. Propyne is hydrated with dilute H₂SO₄ in the presence of HgSO₄. The final product is:
Q10. The number of moles of H₂ needed to fully saturate one mole of vinylacetylene, CH₂=CH–C≡CH, to butane is:
Q11. The number of moles of O₂ required for the complete combustion of one mole of propene, C₃H₆, is:
Q12. A mixture of CH₃Br and C₂H₅Br is treated with sodium metal in dry ether. The number of different alkanes formed is:
Q13. Sodium butanoate, CH₃CH₂CH₂COONa, is heated with soda lime (NaOH + CaO). The hydrocarbon formed is:
Q14. Concentrated aqueous sodium propanoate is electrolysed (Kolbe's method). The products at the anode are:
Q15. Nitration of chlorobenzene with a mixture of concentrated HNO₃ and H₂SO₄ gives mainly:
Q16. Which of the following compounds does NOT undergo Friedel–Crafts alkylation with CH₃Cl/AlCl₃ under ordinary conditions?
Q17. Benzene is treated with excess chlorine in bright sunlight (no halogen carrier). The number of moles of Cl₂ added per mole of benzene is:
Q18. Ethylbenzene is heated with hot alkaline KMnO₄ and the mixture is then acidified. The organic product is:
Q19. The rate-determining step in the hydrolysis of tert-butyl bromide in aqueous ethanol (SN1) is:
Q20. 2-Bromobutane is heated with alcoholic KOH. The major alkene formed (Saytzeff rule) is:
Q21. Which of the following alcohols is NOT oxidised by warm acidified K₂Cr₂O₇ under normal conditions?
Q22. Which of the following gives a yellow precipitate of iodoform (CHI₃) on warming with iodine and sodium hydroxide solution?
Q23. Ethanol is heated with an excess of concentrated H₂SO₄ at 170 °C. If instead excess ethanol is used at 140 °C, the major product changes from ethene to:
Q24. Which of the following does NOT react with dilute aqueous NaOH?
Q25. Which of the following is the strongest acid in water?
Q26. Ethoxyethane is heated with excess hydroiodic acid. The organic product(s) is/are:
Q27. CH₃MgBr is added to solid CO₂ (dry ice) and the product is hydrolysed with dilute acid. The final product is:
Q28. Which of the following aldehydes undergoes aldol condensation in dilute NaOH?
Q29. Which of the following gives a red precipitate on heating with Fehling's solution?
Q30. Ethanoic acid and ethanol (1.0 mol each) react: CH₃COOH + C₂H₅OH ⇌ CH₃COOC₂H₅ + H₂O. The equilibrium constant is K_c = 4.0 (volume cancels). The amount of ester at equilibrium is: