Question

Iron do not burn but iron fillings burn vigorously? Why?

Answer 1

because the rate of reaction depends on the size of the element

iron fillings being really small they burn up unlikr iron

Answer 2

acoording to law of rate of reaction,

the rate of reaction depends upon the size of reactant

when size of reactant is small the rate of reaction is fast and when the size of reactant is big rate of reaction is slow .

the size of iron feeling is small and the size of iron is big .

therefor the iron fillings burn vigorously compare to iron.

Hope this will help you