The equation that shows a chemical change is:
1) C3H8 + 5O2 → 3CO2 + 4H2O
This equation represents the combustion of propane (C3H8) in the presence of oxygen (O2), resulting in the formation of carbon dioxide (CO2) and water (H2O), indicating a chemical transformation of the reactants into different products.
The other equations represent physical changes:
- H2O(s) → H2O(g) (melting and boiling of water)
- NH3(g) → NH3(l) (condensation of ammonia)
- C2H5OH(l) → C2H5OH(g) (evaporation of ethanol)