Question: n is known as the what quantum number
[{'answer': 'Principal', 'provenance': [{'wikipedia_id': '532405', 'title': 'Quantum number', 'start_paragraph_id': 15, 'start_character': 11, 'end_paragraph_id': 15, 'end_character': 20, 'bleu_score': 1.0, 'section': 'Section::::Electron in an atom.:Common terminology.\n'}]}]