What characteristic do noble gases share at room temperature?

Noble gases are known for being colorless and odorless at room temperature. This characteristic is a result of their complete electron shell configuration, which makes them chemically stable and unreactive under normal conditions. Because they do not readily form compounds with other elements, they do not exhibit the vibrant colors associated with reactions or the physical properties of metals.

The other options describe characteristics that do not apply to noble gases. They do not portray bright colors nor do they have a metallic appearance. Additionally, noble gases are known for their lack of reactivity, which distinguishes them from reactive gases. This stability and lack of color contribute to their classification as noble gases, which include helium, neon, argon, krypton, xenon, and radon.