In flame photometry, which color corresponds to potassium emission?

• A. Violet
• B. Red
• C. Yellow
• D. Green

Answer: (A)

In flame photometry, you identify and quantify elements by the color of light their excited atoms emit in the flame. Potassium has a characteristic emission in the violet region when its electrons return from an excited state, due to a specific transition that produces light around 404 nm. This violet glow is a distinctive signature of potassium in the flame, which is why the correct choice is violet. Other colors correspond to emissions from different elements or different transitions, so they don’t indicate potassium.