combution of carbon <basics>

could u plz be a bit clearer regarding the question?

here iam asking that

residue after burnig wood that is ash does not burns whereas it is also carbon.

we can see in the case of diamond, it is carbon and burns completely by giving co₂.

why????residue or ash being carbon do not under go combustion

i think i have made myself clear
please answer soon...........please

Ash content of coal is the non-combustible residue left after coal is burnt. It represents the bulk mineral matter after carbon, oxygen, sulfur and water (including from clays) has been driven off during combustion. Analysis is fairly straightforward, with the coal thoroughly burnt and the ash material expressed as a percentage of the original weight.

its just non combustible

i am very greatful to you yaar

actually my chemistry teacher had told me this