Question: when can sublimation be applied as a process of separation
[{'answer': 'to purify compounds', 'provenance': [{'wikipedia_id': '477661', 'title': 'Sublimation (phase transition)', 'start_paragraph_id': 17, 'start_character': 44, 'end_paragraph_id': 17, 'end_character': 63, 'bleu_score': 1.0, 'section': 'Section::::Purification by sublimation.\n'}]}]