Question

Why is it difficult to burn a heap of green leaves than dry leaves ?

Answer 1

It happens because the green leaves contain moisture. So, as long as water is there, it will use the heat to evaporate. After the water evaporates, temperature increases and as soon as ignition temperature is reached, leaves will burn spontaneously. However, dry leaves don’t have moisture so they reach their ignition temperature faster as compared to green leaves. Hence, they catch fire easily.