In the Reinsch test, which color indicates arsenic?

• A. dull black
• B. blue-black
• C. silver gray
• D. shiny black

Answer: (A)

In the Reinsch test, arsenic is detected by reducing it to metallic arsenic which deposits on a copper surface as a film. This deposit appears as a dull black coating, not shiny or distinctly blue-black or silver-gray. The dull black description matches the characteristic look of the arsenic film formed on copper, making it the best indicator among the options.