Heating ethanol with excess concentrated sulphuric acid produces:

Correct option is D

The correct answer is (d) ethene
Explanation: When ethanol (C2H5OH) is heated with excess concentrated sulfuric acid, it acts as a dehydrating agent. This process involves removing a water molecule (H2O) from the ethanol molecule, which leads to the formation of ethene (C2H4).
Detailed Reaction Mechanism:
1. Formation of Protonated Ethanol: Ethanol reacts with sulfuric acid, which donates a proton (H+) to the oxygen of the ethanol, making the oxygen more electron-rich and the hydrogen of the adjacent carbon more acidic.
2. Elimination of Water: This activated complex then loses a water molecule from the ethyl group (the CH2CH3 part of ethanol), forming a carbocation intermediate (CH3CH2+).
3. Formation of Ethene: The positively charged carbocation (ethyl cation) quickly loses a proton from one of the carbons, resulting in the formation of a double bond between the two carbon atoms, thereby creating ethene (C2H4).
This reaction is a common laboratory method for preparing alkenes, in this case, ethene, and demonstrates the use of sulfuric acid not only as a catalyst but also as a dehydrating agent.