Question

Why are the colours of flames different for different substances?​

Answer 1

Answer:

When you heat an atom, some of its electrons are "excited* to higher energy levels. When an electron drops from one level to a lower energy level, it emits a quantum of energy. ... The different mix of energy differences for each atom produces different colours. Each metal gives a characteristic flame emission spectrum

Answer 2

Flame colour may be different for different substances because on burning they emit waves of different wavelength due to differences in their atomic structures. This is actually a characterstic property of materials. For example, Sodium on burning emits a yellow flame while Potassium emits a lilac flame.