Which spectrum shows a discrete set of lines corresponding to transitions between energy levels?

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

Answer: (A)

Energy levels in atoms are quantized; electrons can only occupy certain discrete energy values. When an electron drops from a higher level to a lower one, the energy difference is released as a photon with a specific energy, which corresponds to a particular wavelength. Because only certain energy differences are allowed, the emitted light appears as a set of distinct wavelengths rather than a continuous range. This creates a line-emission spectrum, where each line marks a specific transition between levels. A ground state is simply the lowest energy level, not a spectrum. A photon is the quantum of light produced during the transition, not the spectrum itself. An orbital is the region where an electron is likely to be found, not a spectrum. So the spectrum that shows discrete lines from transitions between energy levels is the line-emission spectrum.