What determines the glow color of a gas discharge tube? Give examples.

Glow discharge is used in fluorescent lamps, tubes for advertising signs. In this case, the color of the glow depends on the nature of the gas.
For example, an orange-red glow occurs when a gas discharge tube is filled with neon, and a bluish-greenish glow occurs when the tube is filled with argon.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.