122 CHAPTER HYDROCARBONS 1. Acetylenic hydrogens are acidic because [1989] Sigma electron density of C Hbond in acetylene is nearer to carbon, which has 50% s- character Acetylene has only open hydrogen in each carbon Acetylene contains least number of hydrogens among the possible hydrocarbons having two carbons Acetylene belongs to the class of alkynes with molecular formula, CnH2n 2. [1989] Bromine in carbon tetrachloride Bromine in acetic acid Alk KMnO4 Ammonical silver nitrate. Ans: 3. Select the true statement about benzene amongst the following [1989] Because of unsaturation benzene easily undergoes addition There are two types of C Cbonds in benzene molecule There is cyclic delocalisation of pi-electrons in benzene Monosubstitution of benzene gives three isomeric products. Ans: Na HCl in H2O KOH in C2H5OH Zn in alcohol. Ans: 5. Reduction of 2-butyne with sodium in liquid ammonia gives predominantly: [1993] cis - 2 - Butene No reaction trans - 2 - Butene n-butane. Ans: 6. Acompound is treated with NaNH 2 to give sodium salt. Identify the compound [1993] C2H2 C6H6 C2H6 C2H4. 7. Reactivity of hydrogen atoms attached to different carbon atoms in alkanes has the order [1993] Tertiary > Primary > Secondary Primary > Secondary > Tertiary Both Tertiary > Secondary > Primary Ans: 8. When hydrochloric acid gas is treated with propene in presence of benzoyl peroxide, it gives [1993] 2-Chloropropane Allyl chloride No reaction n-propyl chloride. 9. Which of the following compounds has the lowest boiling point? [1994] CH3CH2CH2CH2CH3 CH3CH= CHCH2CH3 CH3CH= CH CH= CH2 CH3CH2CH2CH3 Ans: 4. [1992]
123 10. When CH3Cl and AlCl3 are used in Friedel- Crafts reaction, the electrophile is [1994] Cl + AlCl4 CH3 + AlCl2 + Ans: 11. In the free radical chlorination of methane, the chain initiating step involves the formation of [1994] Chlorine free radical Hydrogen chloride Methyl radical Chloromethyl radical. 12. The alkene R CH= CH2 reacts readily with B2H6 and formed the product Bwhich on oxidation with alkaline hydrogen peroxides produces [1995] Ans: 13. When 3, 3-dimethyl 2-butanol is heated with H2 SO4, the major product obtained is [1995] 2,3-dimethyl 2-butene 3, 3-dimethyl 1- butene 2, 3-dimethyl 1- butene cis & trans isomers of 2, 3-dimethyl 2-butene 14. In the presence of platinum catalyst, hydrocarbon Aadds hydrogen to form n-hexane. When hydrogen bromide is added to Ainstead of hydrogen, only a single bromo compound is formed. Which of the following is A? [1996] CH3 CH2 CH = CH CH2 CH3 CH3 CH2 CH2 CH = CH CH3 CH3 CH = CH CH2 CH2 CH3 CH2 = CH CH2 CH2 CH2 CH3 15. [1997] CH3CH2Cl and NaOH CH3CH2OHand H2 SO4 CH2Cl CH2OH and aqueous NaHCO3 Ans: 16. Which one of the following reactions is expected to readily give a hydrocarbon product in good yields? [1997] 17. In commercial gasolines the type of hydrocarbons which are more desirable, is [1997] branched hydrocarbons straight-chain hydrocarbons aromatic hydrocarbons such as toluene linear unsaturated hydrocarbons 18. Ahydrocarbon Aon chlorination gives Bwhich on heating with alcoholic potassium hydroxide changes into another hydrocarbon C. The latter decolourises Baeyer's reagent and on ozonolysis forms formaldehyde only. Ais [1998] Ethane Butane Methane Ethene 19. The reaction of ethyl magnesium bromide with water would give [1999] Ethane Ethyl alcohol Ethyl bromide Ethyl ether
124 20. Which of the following reagents convert propene to 1-propanol? [2000] H2O, H2 SO4 aqueous KOH MgSO4, NaBH4 /H2O B2H6, H2O2, OH Ans: 21. For the formation of toluene by Friedal Craft reaction, reactants used in presence of anhydrous AlCl3 are [2000] C2H2 and CCl4 CH4 and CaCN2 C6H6 and CH3Cl C2H5 OH and Zn Ans: 22. In preparation of alkene from alcohol using Al2O3 which is effective factor? [2001] Temperature Concentration Surface area of Al2O3 Porosity of Al2O3 23. CH3COCH3 CH3COCH3 + CH3COOH CH3COCH3 + CH3CHO Ans: 25. Reaction of HBr with propene in the presence of peroxide gives [2004] isopropyl bromide 3-bromo propane allyl bromide n-propyl bromide Ans: 26. Using anhydrous AlCl3 as catalyst, which one of the following reactions produces ethylbenzene (PhEt)? [2004] Ans: 27. Which one of the following alkenes will react faster with H2 under catalytic hydrogenation conditions? (R= Alkyl Substituent) [2005] [2001] 24. 28. [2005] [2003] CH3CHO+ CO2
125 Ans: 29. 32. [2007] [2009] 1-butyn-3-ene but-1-yne-3-ene 1-butene-3-yne 3-butene-1-yne Ans: 33. Liquid hydrocarbons can be converted to a mixture of gaseous hydrocarbons by: [2010] Oxidation Cracking Distillation under reduced pressure Hydrolysis Ans: 34. Ans: 30. Which of the compounds with molecular formula C5H10 yields acetone on ozonolysis? [2007] 3-methyl-1-butene cyclopentane 2-methyl-1-butene 2-methyl-2-butene. Ans: 31. [2008] Ans: [2010] 35. The IUPACname of the compound CH 3CH= CHC= CH is [2010] Pent-l-yn-3-ene Pent-4-yn-2-ene Pent-3-en-1-yne Pent-2-en-4-yne Ans: 36. [2011] Ans:
126 38. Which of the following reagents will be able to distinguish between 1-butyne and 2-butyne? [2012] NaNH2 HCl O2 Br2 39. Ans: 37. [2013] 7 p-orbitals and 6 unpaired electrons 7 p-orbitals and 7 unpaired electrons 6 p-orbitals and 7 unpaired electrons 6 p-orbitals and 6 unpaired electrons Ans: 40. [2012] Iodoform test Tollen s reagent test Brady s reagent test Victor Meyer test Ans: [2013] 41. Which of the following chemical system is non aromatic? [2013]
127 5. 1. 6. 7. 2. 8. 3. 9. 10. 4. 11. 12.
128 13. 17. 18. 14. 15. 19. 16. 20.
129 27. 21. 22. 23. 28. 24. 25. 29. 30. 26.
130 41. 31. 32. 33. 34. 35. 36. 37. 38. 39. 40.