Identify the product X in the following reaction.
\( \displaystyle \ce{CH3-CH2-OH} \xrightarrow[443\ \mathrm{K}]{\ce{H2SO4}} \mathrm{X} \)
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Ethene
Alcohols lose a molecule of water when heated with concentrated sulphuric acid (acidic dehydration). The product depends on the temperature:
At 443 K with excess acid, an intramolecular elimination takes place and an alkene forms.
At 413 K with excess alcohol, two molecules of alcohol lose one molecule of water and an ether forms.
\( \displaystyle \ce{C2H5OH} \xrightarrow[443\ \mathrm{K}]{\ce{H2SO4}} \ce{CH2=CH2 + H2O} \)
\( \displaystyle \ce{2C2H5OH} \xrightarrow[413\ \mathrm{K}]{\ce{H2SO4}} \ce{C2H5-O-C2H5 + H2O} \)
The reaction is carried out at 443 K, so X is ethene.
Why the other options are incorrect
Option (2) Diethyl ether — Incorrect. Diethyl ether forms at the lower temperature of 413 K, with ethanol in excess.
Option (3) Acetone — Incorrect. Acetone has three carbon atoms and is a ketone; it cannot form from ethanol, which has two, and it is made by oxidising a secondary alcohol (propan-2-ol).
Option (4) Ethanal — Incorrect. Ethanal is an oxidation product of ethanol (for example with PCC or hot Cu at 573 K); sulphuric acid here acts as a dehydrating agent, not an oxidising agent.
NCERT (2026-27 edition):
By Dehydration of Alcohols
