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 Multiple Choice QuestionsMultiple Choice Questions

1.

The major organic compound formed by the reaction of 1,1,1-trichloroethane with silver powder is

  • acetylene

  • ethene

  • 2-butyne

  • 2-butene


C.

2-butyne

 The reaction is 
2 space CH subscript 3 space minus CCl subscript 3 space rightwards arrow from increment to 6 space Ag of space CH subscript 3 minus straight C identical to straight C minus CH subscript 3 space plus 6 AgCl

422 Views

2.

What is DDT among the following

  • Greenhouse gas 

  • A fertilizer

  • Biodegradable pollutant

  • Non–biodegradable pollutant


D.

Non–biodegradable pollutant

DDT is P,P' - Dichlorodiphenyl trichloro ethane. It was used as an insecticide. DDT is not metabolised very rapidly by animals. It was also discovered to have a high toxicity towards fish. Therefore, It is a non-bio degradable pollutant.

250 Views

3.

In the given transformation, which of the following is the most appropriate reagent?

  • NH2NH2,O-H

  • Zn − Hg/HCl

  • Na,Liq.NH3

  • NaBH4


A.

NH2NH2,O-H

229 Views

4.

2–Hexyne gives trans–2–Hexene on treatment with

  • Pt/H2

  • Li/NH3

  • Pd/BaSO4

  • LiAlH4


B.

Li/NH3



301 Views

5.

An unknown alcohol is treated with the “Lucas reagent” to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what mechanism

  • Secondary alcohol by SN1

  • Tertiary alcohol by SN1

  • Secondary alcohol by SN2

  • Tertiary alcohol by SN2


B.

Tertiary alcohol by SN1

Reaction proceeds through carbocation formation as 30 carbocation is highly stable, hence reaction proceeds through SN1 with 30 alcohol. 

245 Views

6.

The synthesis of alkyl fluorides is best accomplished by

  • free radical fluorination

  • Sandmeyer's reaction

  • Finkelstein reaction

  • Swarts reaction


D.

Swarts reaction

Alkyl fluorides can be prepared by the action of mercurous fluorides or antimony trifluoride (inoragnic fluorides) on corresponding alkyl halide.

This reaction is known as Swarts reaction

CH3Br + AgF → CH3F + AgBr
But, when the action of NaI/acetone takes place on alkyl chloride or bromide alkyl iodide forms. This reaction is called 'Finkelstein reaction.
straight C subscript 2 straight H subscript 5 Cl space rightwards arrow from acetone to NaI of straight C subscript 2 straight H subscript 5 straight I space plus space NaCl
Free radical fluoridation is a highly explosive reaction. So not preferred for the preparation of fluoride.

334 Views

7.

The reaction of propene with HOCl(Cl2+H2O) proceeds through the intermediate:

  • CH3−CH+−CH2−Cl

  • CH3−CH(OH)−C+H2

  • CH3−CHCl−C+H2

  • CH3−C+H−CH2−OH


A.

CH3−CH+−CH2−Cl

CH subscript 3 space minus CH equals CH subscript 2 space rightwards arrow from left parenthesis electrophilic space addition right parenthesis to straight H straight O with straight delta minus on top minus straight C with straight delta plus on top straight l of space stack CH subscript 3 space minus straight C with plus on top straight H space minus CH subscript 2 minus Cl with left parenthesis intermediate right parenthesis below
rightwards arrow with straight O with minus on top straight H on top space CH subscript 3 minus CH left parenthesis OH right parenthesis minus CH subscript 2 minus Cl
763 Views

8.

The product of the reaction given below is:


A.

314 Views

9.

In SN2 reactions, the correct order of reactivity for the following compounds CH3Cl, CH3CH2Cl, (CH3)2CHCl and (CH3)3CCl is

  • CH3Cl > (CH3)2CHCl >CH3CH2Cl > (CH3)3CCl

  • CH3Cl > CH3CH2Cl > (CH3)2CHCl >(CH3)3CCl

  • CH3CH2Cl > CH3Cl >(CH3)2CHCl >(CH3)3CCl

  • (CH3)2CHCl > CH3CH2Cl > CH3Cl >(CH3)3CCl


B.

CH3Cl > CH3CH2Cl > (CH3)2CHCl >(CH3)3CCl

Rate space of space straight S subscript straight N 2 space proportional to fraction numerator 1 over denominator Steric space crowding space of space apostrophe straight C apostrophe end fraction
As steric hindrance (crowding) increases, the rate of SN2 reaction decreases.
The order of reactivity towards SN2 reaction for alkyl halides is 
Primary halides > Secondary halides >Tertiary halides
402 Views

10.

The order of stability of the following carbocations,

  • III>II>I

  • II> III>I

  • I>II>III

  • III>I>II


D.

III>I>II

315 Views