Question

Wavelength of yellow doublets of mercury spectrum and sodium spectrum

Answer 1

The wavelength of Sodium light actually consists of two wavelengths called the D lines.

The dominant yellow emissions you are probably referring to are the doublet located regions.All the above experiment tells that the sodium spectrum consists of two regions and its dominant color is yellow.

So as mercury like those used in some parking lots, emit a yellow (wavelength 589 nm) light. The visible orange light has a wavelength of about 590 nm. The visible red light has a wavelength of about 650 nm.