The light produced when electrons pass through pure neon is
a. blue-green
b. yellow-orange
c. red
d. any color

Question

The light produced when electrons pass through pure neon is
    a. blue-green
    b. yellow-orange
    c. red
    d. any color

anonymous · Answer

According to http://nemesis.lonestar.org/reference/electricity/fluorescent/overview.html see Comparison of Gas Discharge Lighting Colors table and http://en.wikipedia.org/wiki/Visible_spectrum the colour is red

anonymous · Answer

I have a low pressure neon discharge tube. It is used in the lab for spectroscopy.  The last time I viewed the spectrum it was predominantly red  but orange, yellow and green were also present. So d) would be the correct answer.  Do not be confused as the colour of the emission looks completely red there are other electrons at different levels being excited giving rise to emitted photons of various wavelengths when the electrons revert to their original state.  Sodium is predominantly yellow but has green and violet, mercury is predominantly indigo but has yellow and red too.  You can view spectra online to check.

anonymous · Answer

But is neon gas you are using pure? In case if it is mixed with mercury or smth else it is not really surprising thing. As long as I know, mercury in neon gas shifts the color of gas to blue so you can get any colour between red and blue, it is so ONLY in case when NEON gas is not PURE.