Answer: Baeyers test.
- A Tollens test
- B Fehling test
- C Baeyers test
- D Lucas test
Correct answer: C. Baeyers test
Explanation: Baeyers reagent (alkaline KMnO<sub>4</sub>) is decolourised by unsaturated hydrocarbons.
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.