Question

Emission wavelength of potassium ions is _______ nm.

• A. \( 589 \)
• B. \( 622 \)
• C. \( 670 \)
• D. \( 766 \)

Hint:

Think of potassium flames having a characteristic lilac or pale violet color, which corresponds to its emission spectrum with the strongest line at 766 nm in the red/far-red region.

Answer 1

The Correct Option is D

In atomic emission spectroscopy, when potassium ions are excited in a flame, they emit light at characteristic wavelengths. The most prominent emission line for potassium is in the red region of the spectrum, specifically at 766 nm. While potassium also has other emission lines, the 766 nm line is the most intense and is typically used for its detection and quantification in techniques like flame photometry. The sodium emission line is at 589 nm (yellow), lithium is at 670 nm (red), and other elements have different characteristic emission wavelengths.