Question

when does a flame formed​

Answer 1

Answer:

all

This is due to incandescence of very fine soot particles that are produced in the flame. With increasing oxygen supply, less black body-radiating soot is produced due to a more complete combustion and the reaction creates enough energy to excite and ionize gas molecules in the flame, leading to a blue appearance.

Answer 2

Answer:

when flame formed there will be smoke also