What is the color of bromine gas?

• A. Orange
• B. Pale yellow
• C. Green
• D. Red-Brown

Answer: (A)

The color of bromine gas reflects how halogen colors change down the group: lighter halogens are pale in color, while heavier ones are deeper. Bromine is a heavier halogen, and its diatomic gas appears reddish-brown because it absorbs light in the blue-green part of the spectrum, letting the red-brown light be seen. Bromine is also a liquid at room temperature with a reddish-brown color, and its vapor shares that hue. So the correct color is red-brown. The orange option isn’t correct for bromine; chlorine gas is greenish-yellow and fluorine gas is pale yellow, while iodine vapor is violet.