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COMEDK 2025 Evening Solved Paper

Question : 95 of 180

Marks: +1, -0

Choose the incorrect statement.

Cresols are less acidic than Phenol because electron releasing groups do not favour formation of Phenoxide ion.
Ethanol acts as Nucleophile when the $\mathrm{O}-\mathrm{H}$ bond is broken and acts as Electrophile on getting protonated.
In the acid catalysed hydration of Ethene, an Oxonium ion is formed when it reacts with $\mathrm{H}_3 \mathrm{O}^{+}$ and a Carbocation is formed when the Oxonium ion reacts with water.
In the reaction between Ethanol and Conc. $\mathrm{H}_2 \mathrm{SO}_4$ at 413 K , an Oxonium ion is formed when Ethanol gets protonated.

Solution:

Concept:

The correct sequence in acid-catalysed hydration of ethene is protonation first, then nucleophilic attack.

Explanation:

Step 1: Ethene is protonated by

\mathrm{H_3O^+}

to form a carbocation.

\mathrm{CH_2=CH_2 + H_3O^+ \rightarrow CH_3-CH_2^+ + H_2O}

Step 2: The carbocation is attacked by water to give an oxonium ion.

\mathrm{CH_3-CH_2^+ + H_2O \rightarrow CH_3-CH_2OH_2^+}

Step 3: Deprotonation of the oxonium ion yields ethanol.

Option C says an oxonium ion forms first, then a carbocation forms when it reacts with water – this reverses the actual order and is therefore false.

All other statements (A, B, D) are correct.

Answer:

The incorrect statement is Option C.

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