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 QuestionsLong Answer Type

Advertisement

151.

Discuss the free radical mechanism of addition of HBr to propene.
Or
Give the mechanism of addition of HBr to propylene in the presence of peroxide.


Propylene reacts with HBr in the presence of peroxide to form 1-bromo propane.



Mechanism: It proceeds with free radical mechanism and consists of the following steps:
Step I. Chain initiating step: Organic peroxide undergoes homolysis to from free radicals.



Step II. Chain propagating step: The bromine radical then adds to propene molecule in such a way that the more stable free radical is produced. 



As the secondary free radical is more stable, it will be preferably formed. The secondary free radical then reacts with HBr to form 1-bromo-propane and bromine radical.



This bromine radical continues the chain by repeating the chain propagating step.

Step III. Chain terminating step: At the end, the reaction stops by coupling the radicals.




276 Views

Advertisement
152. Write IUPAC names of the products obtained by addition reactions of HBr to hex-1-ene:
(i) in the absence of peroxide and
(ii) in the presence of peroxide.

1449 Views

153.

The addition of HBr to propene yields 2-broniopropane, while in the presence of benzoyl peroxide, the same reaction yields 1-bromopropane. Explain and give mechanism. 

410 Views

 Multiple Choice QuestionsShort Answer Type

154.

Why peroxide effect is shown only by HBr and not by HCl or HI?
Or
Explain why Kharasch effect is shown by HBr only and not by HCl or HI.

1832 Views

Advertisement

 Multiple Choice QuestionsLong Answer Type

155. Discuss the mechanism of formation of halohydrin.
237 Views

156.

How do alkenes react with sulphuric acid? Discuss its mechanism.

370 Views

 Multiple Choice QuestionsShort Answer Type

157.

Write a short note on hydroboration oxidation.

247 Views

 Multiple Choice QuestionsLong Answer Type

158.

What is ozonolysis? What is its significance?

821 Views

Advertisement

 Multiple Choice QuestionsShort Answer Type

159.

Write IUPAC names of the products obtained by the ozonolysis of the following compounds:
Pent - 2-ene 

297 Views

160.

Write IUPAC names of the products obtained by the ozonolysis of the following compounds:
 3, 4-Dimethlhept-3-ene

231 Views

Advertisement