Question: the main difference between isotopes of the same element
[{'answer': 'its number of neutrons', 'provenance': [{'wikipedia_id': '19600416', 'title': 'Isotope', 'start_paragraph_id': 3, 'start_character': 270, 'end_paragraph_id': 3, 'end_character': 292, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}, {'provenance': [{'wikipedia_id': '19600416', 'title': 'Isotope', 'start_paragraph_id': 3, 'start_character': 0, 'end_paragraph_id': 3, 'end_character': 450, 'bleu_score': 0.9451526628827591, 'meta': {'yes_no_answer': 'NONE', 'annotation_id': 10338081742022332290}, 'section': 'Section::::Abstract.'}]}]