Hydrocarbons Te...

Direction (Q. Nos. 1 - 8) This section contains 8 multiple choice questions. Each question has four choices (a), (b), (c) and (d), out of which ONLY ONE option is correct.

Q. How many distinct alkynes exist for C₆H₁₀ which gives effervescence on heating with Na?

Which of the following improperly describes the physical property of an alkyne?

What two atomic or hybrid orbitals overlap to form the carbon-carbon σ (sigma) bond in ethyne?

Which of the following statements correctly describes the general reactivity of alkynes?

How many different isomeric alkynes on catalytic hydrogenation gives the same 3-ethyl hexane?

An organic compound X (C₆H₁₃Br) is optically active. X on treatment with (CH₃)₃COK in (CH₃)₃COH gives Y (C₆H₁₂), a major product. Y on treatment with Br₂— CCI₄ in the presence of FeBr₃ gives a dibromide which on further treatment with NaNH₂ gives C₆H₁₀ which is still optically active. Hence, X and Y respectively are

When 2,3-dibromobutane is treated with KOH in ethanol, 2-bromo-2-butene is formed which does not undergo further dehydrobromination to form 2-butyne under similar condition because

When vicinal dibromide is heated with KOH in ethanol (~ 200°C), double dehydrohalogenation takes place giving alkyne. Which of the following fails to give alkyne according to this procedure?

Direction (Q. Nos. 9 - 12) This section is based on Statement I and Statement II. Select the correct answer from the codes given below.

Q.

Statement I : When 1-butyne is treated with NaNH₂, sodium salt is formed.

Statement II : NH₃ is w eaker acid than .

Statement I : Treatment of either 1,2-dibromobutane or 2,2-dibromobutane with NaNH₂ gives the same 1-butyne.

Statement II : NaNH₂ forms salt with terminal alkyne which makes possible the above observation.

Statement I : Propyl lithium on reaction with 1-bromo-1-pentyne gives 4-octyne.

Statement II : Propyl lithium acts as a very strong nucleophile, brings about SN₂ reaction of halides.

Statement l : C₆H₅MgBr with propyne gives 1-phenyl propyne.