It is difficult to burn a heap of green leaves but dry leaves catch fire easily. Explain.

The difference in flammability between green and dry leaves is primarily due to their moisture content:

1. Moisture Content: Green leaves contain a higher moisture level, acting as a natural barrier against ignition. The moisture absorbs heat, making it difficult for the leaves to reach their ignition temperature.

2. Ignition Temperature: Dry leaves, with lower moisture content, have a lower ignition temperature. They readily ignite as the absence of moisture reduces the energy required for combustion.

3. Heat Absorption: Moisture in green leaves absorbs heat during the initial burning stages, diverting it away from the leaves and impeding rapid temperature increase necessary for ignition.

4. Combustible Components: Dry leaves contain flammable components like cellulose and lignin, enabling rapid oxidation and easier combustion when dry.

In summary, the higher moisture content in green leaves hinders ignition by absorbing heat, while dry leaves, with lower moisture and combustible components, readily reach their ignition temperature, making them more prone to catching fire.