Question

Why do all materials turn only black when burnt why not blue or pink?

Answer 1

Due to the formation of carbon which is black in colour..all materials turn black after its burnt..Constituents of most of the fuels are also hydrocarbons..and also of many materials too..Black can also be the colour of the fuel..

Answer 2

Not all materials. You can say almost all things turn black after burning. This is because of the carbon left behind. Almost all things that we see around us like paper, wood are made of up hydrocarbons that after getting burnt turn black. The presence of carbon ( which is black) leads to this commonly observed phenomenon