(A) Styrene is more reactive than propylene towards cationic polymerization.
(R) The carbocation resulting from styrene is more stable than that resulting from propylene.

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Both (A) and (R) are true and (R) is the correct explanation of (A)

Both (A) and (R) are true but (R) is not the correct explanation of (A)

(A) is true but (R) is false

Both (A) and (R) are false

answer is A.

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Detailed Solution

Cationic polymerization is a type of chain-growth polymerization that involves the formation of a carbocation intermediate.
The carbocation intermediate is formed by the addition of a proton (H⁺) to the double bond of the monomer.
The resulting carbocation intermediate is then attacked by another monomer molecule to form a longer chain.
Styrene is more reactive than propylene towards cationic polymerization.
The reason for this is that the carbocation resulting from styrene is more stable than that resulting from propylene.
The stability of a carbocation depends on the number of substituents attached to the carbocation center.
The more the number of substituents attached to the carbocation center, the more stable the carbocation.
In the case of styrene, the carbocation intermediate formed after protonation has an aromatic ring attached to it, which provides significant stabilization due to resonance.
On the other hand, in the case of propylene, the carbocation intermediate has only one alkyl group attached to it, which provides less stabilization compared to an aromatic ring.
Therefore, both Assertion (A) and Reason (R) are true, and Reason (R) correctly explains Assertion (A).

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