Which of the following statements best describes the emission spectrum of hydrogen?

• A. It is a continuous spectrum with all visible wavelengths present.
• B. It shows only a single line in the visible region.
• C. It is identical to the emission spectrum of helium.
• D. It consists of discrete lines corresponding to specific wavelengths emitted when electrons transition between energy levels.

Answer: (D)

Verified step by step guidance

1. Understand that the emission spectrum of hydrogen arises from electrons transitioning between quantized energy levels in the atom.
2. Recall that when an electron in a hydrogen atom drops from a higher energy level to a lower one, it emits a photon with energy equal to the difference between those levels.
3. Recognize that the energy of the emitted photon corresponds to a specific wavelength, so the emission spectrum consists of discrete lines rather than a continuous range of wavelengths.
4. Note that these discrete lines form series (such as the Balmer series) that appear at specific wavelengths in the visible and other regions of the electromagnetic spectrum.
5. Conclude that the emission spectrum of hydrogen is unique and consists of distinct lines, not a continuous spectrum or a single line, and it differs from the emission spectra of other elements like helium.