Elements can be identified based on their emission spectrum because each element: emits a characteristic set of discrete wavelengths, according to its electronic energy levels emits a characteristic set of discrete wavelengths, depending on the amount of energy applied has its own inherent, identifiable color to start with has the same basic pattern of spectral lines with few exceptions

Answer is: emits a characteristic set of discrete wavelengths, according to its electronic energy levels.

Emission spectrum of a chemical element is the spectrum of frequencies emitted due to an atom making a transition from a high energy state to a lower energy state.

Each transition has a specific energy difference.

Each element's emission spectrum is unique.

gas

explanation:

smoke is the matter of a gas