Assertion:
Crown ether acts as phase transfer catalysis and increases $S_{N} 2$ reactivity.

Reason:
They strongly complex cation and leave anion (nucleophile) with increased reactivity.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

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Assertion is correct but Reason is incorrect

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Assertion is incorrect but Reason is correct

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Both Assertion and Reason are incorrect

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Solution

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
Crown Ethers act as good complexing agents. The cations are trapped in the rings with oxygens forming dative bonds with the metal ion. With the trapping of metal ions, the nucleophile becomes more powerful and thus the rate of reaction increases.

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Assertion: Crown ether acts as phase transfer catalysis and increases SN2 reactivity.Reason: They strongly complex cation and leave anion (nucleophile) with increased reactivity.

Assertion:
Crown ether acts as phase transfer catalysis and increases $S_{N} 2$ reactivity.

Reason:
They strongly complex cation and leave anion (nucleophile) with increased reactivity.