Answer: Dilute H2SO4 with HgSO4.
- A Alkaline KMnO4 (cold)
- B Dilute H2SO4 with HgSO4
- C Ozone followed by Zn/H2O
- D Hot concentrated HNO3
Correct answer: B. Dilute H2SO4 with HgSO4
Explanation: Markovnikov hydration of propyne (dilute H2SO4/HgSO4) gives an enol that tautomerises to propanone.
Going from a single to a triple bond between carbons increases the s-character of hybridisation (sp³→sp²→sp), shortening the bond and locking the geometry, while increasing π-bond reactivity (alkenes and alkynes readily undergo addition reactions that alkanes don't).
Concept context
The simplest organic compounds made only of carbon and hydrogen. Covers alkanes, alkenes, alkynes, and aromatic compounds like benzene. Learn preparation methods, key reactions, and physical properties.