Isoprene's Properties as a Hydrocarbon Alkene

Steps:

• Identify isoprene as C5H8, a conjugated diene and type of alkene hydrocarbon.
• Verify property 1: Hydrocarbons like isoprene undergo combustion, burning in air to produce CO2 and H2O.
• Verify property 2: Alkenes react with bromine via electrophilic addition, decolourising aqueous bromine solution.
• Verify property 3: Isoprene polymerizes via addition reactions to form natural rubber and synthetic polymers.

Why A is correct:

• Isoprene exhibits all three properties due to its alkene structure, enabling combustion (exothermic reaction with O2), halogen addition (Br2 unsaturation test), and polymerization (monomer linkage).

Why the others are wrong:

• B omits property 2, but isoprene's double bonds react with Br2.
• C omits property 3, but isoprene is a key monomer for polyisoprene.
• D omits property 1, but as a flammable hydrocarbon, it burns readily.

Final answer: A