Question

Assertion (A): HBr addition to alkenes gives Markonikov addition. Reason (R): HBr addition to alkene in the presence of peroxide gives Anti-Markonikov addition as the reaction proceeds via radical mechanism.

• A. Both (A) and (R) are correct and (R) is the correct explanation of (A)
• B. Both (A) and (R) are correct but (R) is NOT the correct explanation of (A)
• C. (A) is correct but (R) is not correct
• D. (A) is not correct but (R) is correct

Hint:

Ionic = Markovnikov (stable carbocation); Radical + Peroxide = Anti-Markovnikov (stable radical).

Answer 1

The Correct Option is B

Step 1: Concept Electrophilic addition of HBr to alkenes typically follows Markovnikov's rule, where the hydrogen adds to the carbon with more hydrogens.

Step 2: Meaning The "Peroxide Effect" (Kharasch effect) changes the mechanism from ionic to free-radical.

Step 3: Analysis Assertion (A) is a general fact regarding standard ionic conditions. Reason (R) is also a correct fact describing the radical pathway. However, the existence of an anti-Markovnikov radical pathway does not explain why the standard ionic pathway follows Markovnikov's rule.

Step 4: Conclusion Both statements are true independently, but the Reason is not the explanation for the Assertion. Final Answer: (2)