Final answer:
The element used in advertising signs for the bright, reddish-orange glow is neon. Neon is a noble gas that produces a reddish glow when an electric current is passed through it.
Step-by-step explanation:
Chemistry
The *unreactive, gaseous* element used in *advertising signs* for the *bright, reddish-orange glow* it produces when an electric current is passed through it is neon. Neon is a noble gas that can be found in neon signs and lamps. When an electric spark is passed through a tube containing neon at low pressure, it generates the distinct red glow that is commonly associated with neon signs. The red color is due to the emission spectrum of neon.