Which gas color is Orange?

• A. Fluorine gas
• B. Chlorine gas
• C. Bromine gas
• D. Iodine gas

Answer: (C)

The color of a gas comes from which wavelengths of light it absorbs and which it transmits. For halogen gases, the absorbed wavelengths shift as you go down the group, so their visible colors differ.

Bromine’s vapor absorbs blue-green light, so the light that passes through it appears orange-red. That’s why the gas is observed as orange in color. (Note: bromine is a liquid at room temperature, but its vapor still shows the orange color.)

Fluorine gas is a pale yellow, chlorine gas is greenish-yellow, and iodine gas is violet. These colors reflect the different energies of light absorbed by each halogen, which change with the size and electronic structure of the molecules as you move down the group.