Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Treatment of bromine water with propene yields 1-bromopropan-2-ol. Reason (R) : Attack of water on bromonium ion follows Markovnikov rule and results in 1-bromopropan-2-ol. In the light of the above statements, choose the most appropriate answer from the options given below :

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)

Alcohols Phenols and Ethers PYQ — JEE Main 2021 · 31 Aug · Shift 1 · Q7 with Solution

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Correct answer: C

When an alkene reacts with bromine water, it forms a bromonium ion intermediate first.

For propene, the double bond is: $\mathrm{CH_3-CH=CH_2}$

Addition of $\mathrm{Br_2}$ gives a cyclic bromonium ion.

Then water attacks this bromonium ion and opens the ring.

In the bromonium ion, the more substituted carbon bears greater partial positive character. Therefore, water attacks the more substituted carbon.

This is equivalent to Markovnikov-type orientation for halohydrin formation:

So for propene: $\mathrm{CH_3-CH=CH_2 \xrightarrow{Br_2/H_2O} CH_3-CH(OH)-CH_2Br}$

This product is named: $\mathrm{1\text{-}bromopropan\text{-}2\text{-}ol}$

Hence, Assertion (A) is true.

Reason says: attack of water on bromonium ion follows Markovnikov rule and results in $\mathrm{1}$ -bromopropan- $\mathrm{2}$ -ol.

This is correct, because in halohydrin formation from an unsymmetrical alkene:

So Reason (R) is also true.

Yes. The assertion is true because water attacks the bromonium ion at the more substituted carbon, giving the observed product.

Therefore, (R) is the correct explanation of (A).

$\boxed{\text{C}}$

$\boxed{\text{C}}$