When metal ions from Group I and Group II are heated in a flame, what observable phenomenon typically occurs?

• A. They form precipitates in the flame.
• B. They produce a pungent odor.
• C. They dissolve completely in the flame.
• D. They emit characteristic colors due to electronic transitions.

Answer: (D)

Verified step by step guidance

1. Understand that when metal ions from Group I and Group II are heated in a flame, their electrons absorb energy and become excited to higher energy levels.
2. Recognize that as these excited electrons return to their original lower energy states, they release energy in the form of light.
3. Know that the wavelength (color) of the emitted light is characteristic of the specific metal ion, due to unique electronic configurations.
4. Recall that this emission of light is the basis for flame tests, a qualitative analytical technique used to identify metal ions based on the color they produce.
5. Conclude that the observable phenomenon is the emission of characteristic colors, not the formation of precipitates, odors, or dissolution.