Which gas is most commonly used inside a neon sign to produce its characteristic red-orange glow?

• A. Krypton (Kr)
• B. Argon (Ar)
• C. Helium (He)
• D. Neon (Ne)

Answer: (D)

Verified step by step guidance

1. Understand that neon signs produce light by passing an electric current through a gas inside a sealed tube, causing the gas atoms to become excited and emit light as they return to their ground state.
2. Recall that different gases emit different colors of light when excited due to their unique electronic energy levels and emission spectra.
3. Identify that the characteristic red-orange glow of a neon sign is specifically due to the emission spectrum of neon gas (Ne), which is distinct from other noble gases like krypton, argon, or helium.
4. Recognize that while other gases like argon or krypton can be used in lighting applications, the classic red-orange color is uniquely produced by neon gas.
5. Conclude that the gas most commonly used inside a neon sign to produce its characteristic red-orange glow is neon (Ne).