Question

Can you provide a good explanation on the colour of fire? (Thank you)

Answer 1

Usually the colour of flame will be different for different type of materials
When we burn organic fuels like wood, paper etc we will be getting yellow flame due to incomplete combustion with lot of smoke

But when we burn organic fuels like petrol, LPG, ethanol in complete supply of air we will be getting blue flame without any smoke

Apart from this two common colours of flame we will be having some special characterized colours.
For example burning a mixture containing strontium chloride will give dark pink colour.

Burning a mixture containing barium salts gives green colour flame

Burning metals like magnesium will give bright silvery white light

All these flames will have their own special colours because of the jump of electron from one orbit to another orbit.