What happens in the final step of the six-step preparation process?

• A. Crystals filtered off, washed with distilled water, dried between filter paper
• B. Crystals discarded after washing
• C. Crystals dissolved again in filtrate
• D. No further action is required after drying

Answer: (A)

This question tests how crystallization purification is completed. After crystals have formed, you first separate them from the liquid by filtration, then rinse them with distilled water to remove any soluble impurities that clung to the crystals. Distilled water is used so no extra ions contaminate the product. Finally, you dry the crystals between filter papers to remove all moisture, leaving a dry, pure sample and preventing loss of fine crystals. Other options would either leave impurities, undo the purification by dissolving the crystals again, or leave the product wet.