CBSE Class 11 Chemistry HOTs Hydrocarbons

Question. On mixing a certain alkane with chlorine and irradiating it with ultraviolet light, it forms only one monochloroalkane. This alkane could be
(a) pentane
(b) isopentane
(c) neopentane
(d) propane
Answer : C

Question. Addition of Br₂ to trans-2-butene would give a product which is
(a) chiral
(b) meso
(c) racemic
(d) optically active
Answer : B

Question. The addition of HI in the presence of peroxide catalyst does not follow anti-Markovnikov's rule because
(a) HI is a strong reducing agent.
(b) H-I bond is too strong to be broken homolytically.
(c) I atom combines with H atom to give back HI.
(d) Iodine atom is not reactive enough to add across a double bond.
Answer : B

Question. cis-2-Butene has higher boiling point than the trans-analog. It is because of
(a) hydrogen bonding in the cis-isomer
(b) higher molecular mass of the cis-isomer
(c) van der Waal forces in the cis-isomer
(d) polarity in the cis-isomer.
Answer : D

Question. 1, 3-Butadiene when treated with Br₂ gives
(a) 1, 4-dibromo-2-butene
(b) 1, 3-dibromo-2-butene
(c) 3, 4-dibromo-1-butene
(d) 2, 3-dibromo-2-butene
Answer : A

Question. 2-Butene can be obtained by the electrolysis of an aqueous solution of
(a) 1, 2-Dimethylmaleic acid
(b) 2, 2-Dimethylbutandioic acid
(c) 3, 3-Dimethylbutandioic acid
(d) 2, 3-Dimethylbutandioic acid
Answer : D

Question. Which of the following reagents convert propene to 1-propanol?
(a) H₂ O, H₂SO₄
(b) Aqueous KOH
(c) MgSO₄, NaBH4/H₂O
(d) B₂H₆, H2O₂, OH^–
Answer : D

Question. When hydrochloric acid gas is treated with propene in presence of benzoyl peroxide, it gives
(a) 2-Chloropropane
(b) Allyl chloride
(c) n-Propyl chloride.
(d) No reaction
Answer : A

Question. Which of the following would not give 2- phenylbutane as the major product in a Friedel-Crafts alkylation reaction ?
(a) 1-butene + HF
(b) 2-butanol + H₂SO₄
(c) Butanoyl chloride + AlCl₃ then Zn, HCl
(d) Butyl chloride + AlCl₃
Answer : C

Question. Reaction of hydrogen bromide with propene in the absence of peroxide is a/an
(a) free radical addition
(b) nucleophilic addition
(c) electrophilic substitution
(d) electrophilic addition
Answer : D

Question. One mole of propanone and one mole of formaldehyde are the products of ozonolysis of one mole of an alkene. The alkene may be
(a) 2-methylpropene
(b) 2, 2-dimethyl-1-butene
(c) propene
(d) 2-butene
Answer : A

Question. In the presence of peroxide, HCl and HI do not give anti-Markownikoff’s addition of alkenes because:
(a) One of the steps is endothermic in HCl and HI
(b) Both HCl and HI are strong acids
(c) HCl is oxidizing and the HI is reducing
(d) All the steps are exothermic in HCl and HI
Answer : A

Numeric Value Answer

Question. On conversion into the Grignard reagent followed by treatment with water, how many alkyl bromides would yield isopentane?
Answer : 4

Question. Number of hydrocarbons formed when C₂H₅Br and CH₃–CH₂–CH₂–Br are treated with Na in the presence of dry ether is ______.
Answer : 7

Question. How many number of moles of H₂ is used for the complete hydrogenation of the given compound in the presence of a metal catalyst?

Answer : 7

Question. Total no. of alkynes that on catalytic reduction gives 3-ethyl-4-methylheptane ______.
Answer : 3