Which statement about ammonium carbonate addition is true?

• A. Add ammonium carbonate to the ash at roughly 5 ml per gram of ash.
• B. Add ammonium carbonate to the ash after drying the ash at 180 °C.
• C. Ammonium carbonate should never be added to ash.
• D. The amount of ammonium carbonate has no bearing on the procedure.

Answer: (A)

The key idea is that adding ammonium carbonate must be done in a precise, proportional way to create the proper reaction conditions for the ash sample. Using a defined volume per unit mass ensures every gram of ash experiences the same amount of reagent, which is essential for consistent mixing, reaction progress, and reliable results. The recommended ratio of roughly 5 ml per gram of ash gives enough ammonium carbonate to interact with the ash without overly diluting the sample. Statements that imply you can add it at a different stage (such as after drying) or that the amount doesn’t matter or that it should never be added ignore the need for a controlled, reproducible preparation step.