Question: what is the most abundant chemical on earth
[{'answer': 'iron', 'provenance': [{'wikipedia_id': '392828', 'title': 'Abundance of the chemical elements', 'start_paragraph_id': 1, 'start_character': 140, 'end_paragraph_id': 1, 'end_character': 144, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '392828', 'title': 'Abundance of the chemical elements', 'start_paragraph_id': 25, 'start_character': 0, 'end_paragraph_id': 25, 'end_character': 294, 'bleu_score': 0.885632718431904, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 17398714357563687343}, 'section': 'Section::::Earth.\n'}]}]