A diagram or graph that indicates the degree to which a substance emits radiant energy with respect to wavelength?

• A. Continuous spectrum
• B. Photon
• C. Ground state
• D. Line-emission spectrum

Answer: (D)

The idea being tested is how emission is distributed across wavelengths when a substance releases radiant energy. In atoms, light comes from electrons dropping between discrete energy levels, so the emitted energy appears at specific wavelengths. A diagram that plots emission intensity versus wavelength will show peaks at those particular wavelengths, which is exactly what a line-emission spectrum represents—the spectrum consists of distinct lines rather than a smooth, continuous spread. This distinguishes it from a continuous spectrum, where all wavelengths blend together with no gaps. A photon is just a single quantum of light, not a chart of emission across wavelengths, and the ground state is simply the lowest energy level, not a spectrum.