When added to boric acid and then ignited, it burns with a green-bordered flame:

When added to boric acid and then ignited, it burns with a green-bordered flame:

• A. Hexane
• B. Ethanol
• C. Butanol
• D. Methanol

Answer: (D)

The green flame comes from boron in the flame test. When boric acid is heated with a fuel, boron-containing species enter the flame and emit green light. A clean, low-soot fuel like methanol carries boron into the flame without adding much color of its own, so the green boron emission is visible as a green-bordered flame. Other fuels—such as hydrocarbons or larger alcohols—tend to burn with colors or soot that mask the boron’s green glow, making methanol the best choice to produce that distinctive green border.

The green flame comes from boron in the flame test. When boric acid is heated with a fuel, boron-containing species enter the flame and emit green light. A clean, low-soot fuel like methanol carries boron into the flame without adding much color of its own, so the green boron emission is visible as a green-bordered flame. Other fuels—such as hydrocarbons or larger alcohols—tend to burn with colors or soot that mask the boron’s green glow, making methanol the best choice to produce that distinctive green border.