Question

ch9. q1
the light given off by an electric discharge through sodium vapor is
of a single wavelength
white light
a continuous spectrum
an emission spectrum

Explanation:

When an electric discharge passes through sodium vapor, it emits light. Sodium vapor does not emit a single wavelength (it has characteristic lines), it is not white light (which has a full range of visible wavelengths), and it is not a continuous spectrum (continuous spectra are from hot solids/liquids or dense gases). An emission spectrum is produced when atoms in a gas (like sodium vapor here) are excited (by electric discharge) and then emit light as electrons transition to lower energy levels.

Answer:

an emission spectrum