How does your eye see the light compared to the eye aided by the diffraction gratingatomic emission spectra

Question

how does your eye see the light compared to the eye aided by the diffraction grating

Atomic Emission Spectra

A hydrogen discharge tube is a slim tube containing hydrogen gas at low pressure with an electrode at each end. If you put a high voltage across this (say, 5000 volts), the tube lights up with a bright pink glow.

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just did the assignment and the answer was #1 +2 n