When ethanol is heated with conc. H₂ SO₄, a gas is produced. The compound formed, when this gas is treated with cold dilute aqueous solution of Baeyer's reagent, is

Solution

Chemistry ma’am · 3 steps

First make the gas, then remember: cold, dilute KMnO₄ only adds two OH groups across the double bond.

1. Make the gas. Hot concentrated H₂SO₄ removes a water molecule from ethanol. This dehydration gives ethene gas.

   CH₃CH₂OH →(conc. H₂SO₄, 443 K) CH₂=CH₂ + H₂O

2. Baeyer's reagent. Baeyer's reagent is cold, dilute, alkaline KMnO₄. Under these mild conditions it does not break the C=C bond. It adds one OH group to each carbon, giving a 1,2-diol, and the purple colour fades.
3. So. Ethene becomes HOCH₂-CH₂OH, ethane-1,2-diol, which is glycol, option (c).

The idea to keep. Cold dilute alkaline KMnO₄ only hydroxylates an alkene to a diol. Hot or acidic KMnO₄ cleaves the C=C bond and gives carbonyl compounds or acids.

Answer from the NTA final answer key. Solution by PrepWiser.