Which of the following acts like fingerprints that identify atoms and molecules?

• A. Melting point
• B. Density
• C. Atomic mass
• D. Spectral lines

Answer: (D)

Verified step by step guidance

1. Understand that each atom or molecule can absorb or emit light at specific wavelengths, creating a unique pattern known as spectral lines.
2. Recognize that spectral lines arise from electronic transitions between energy levels within atoms or molecules, which are unique to each species.
3. Compare this uniqueness to fingerprints, meaning no two different atoms or molecules have the exact same spectral line pattern.
4. Note that properties like melting point, density, and atomic mass are not unique enough to serve as definitive identifiers because different substances can share similar values.
5. Conclude that spectral lines are the most precise and reliable way to identify atoms and molecules, acting like their fingerprints.