Previous Year Papers

Download Solved Question Papers Free for Offline Practice and view Solutions Online.

Test Series

Take Zigya Full and Sectional Test Series. Time it out for real assessment and get your results instantly.

Test Yourself

Practice and master your preparation for a specific topic or chapter. Check you scores at the end of the test.
Advertisement

 Multiple Choice QuestionsMultiple Choice Questions

611.

An incorrect statement with respect to SN1 and SN2 mechanisms for alkyl halide is

  • A strong nucleophile in an aprotic solvent increases the rate or favours SN2 reaction.

  • Competing reaction for an SN2 reaction is rearrangement.

  • SN1 reactions can be catalysed by some Lewis acids.

  • A weak nucleophile and a protic solvent increases the rate or favours SN1 reaction.


Advertisement

612.

The hydrolysis of optically active 2-bromobutane with aqueous NaOH result in the formation of

  • (+) butan -2-ol

  • (-) butan-2-ol

  • (±) butan-1-ol

  • (±) butan-2-ol


D.

(±) butan-2-ol

In case of organic reactions, to differentiate between first order and second order kinetics, you should check the stability of carbocation. If carbocation is stable, then it will follow first order kinetics otherwise second order kinetics Since,2°- carbocation is stable so given reaction follows first order kinetics.
Usually 1° carbocatlon follows second order kinetics and 2° or 3° carbocation follows first order kinetics.The reaction between 2-bromobutane with aqueous NaOH follows first order kinetics, i.e the rate of the reaction depends upon the concentration of 2- bromobutane (SN1 mechanism).

Smee, the 2-bromobutane is optically active than the product is a racemic mixture. This is because carbocations are as intermediates in SN1 reactions Smee, carbocation being sp2 -hybridised is planar (achiral) species, the attack of the nucleophle on it can occur from both the faces (front and rear) with almost equal case giving a 50-50 mxture of two enantiomers. So, 2 bromobutane gives racemic of(±)butan-2-ol


Advertisement
613.

Predict the product 'C' in the following series of reactions:

CH3-COOH PCl5 A Anhy. AlCl3C6H6 B CH3MgBr C

  • CH3CH(OH)C6H5

  • CH3CH(OH)C2H5

  • (CH3)2C(OH)C6H5


614.

In Grignard reagent the carbon-magnesium bond is:

  • electrovalent

  • covalent

  • dative

  • hydrogen bonding


Advertisement
615.

In the reaction,

CH3CH2C ≡ CH (ii) H2O(i) O3 Products

Products will be:

  • CH3COCH3

  • CH3COCH2OH

  • CH3COOH + HCOOH

  • CH3CHO + HCHO


616.

Ethyl alcohol can be prepared from Grignard reagent by the reaction of :

  • HCHO

  • R2CO

  • RCN

  • RCOCl


617.

The compound formed on heating chlorobenzene with chloral in the presence of concentrated sulphuric acid is

  • gammexane

  • DDT

  • freon

  • hexachloroethane


618.

Ethyl alcohol is used as a preservative for chloroform because it :

  • prevent aerial oxidation of chloroform

  • prevents decomposition of chloroform

  • decomposes phosgene to CO and Cl2

  • removes phosgene by converting it to ethyl carbonate


Advertisement
619.

Protic solvent is

  • diethyl ether

  • n-hexane

  • acetone

  • ethanol


620.

Mustrad gas is

  • oil gas

  • poisonous gas

  • fuel gas

  • life gas


Advertisement