Question: where do the tetrahedra bond to each other
[{'answer': '≈ 109.5 °', 'provenance': [{'wikipedia_id': '3797882', 'title': 'Tetrahedral molecular geometry', 'start_paragraph_id': 1, 'start_character': 196, 'end_paragraph_id': 1, 'end_character': 209, 'bleu_score': 1.0, 'section': 'Section::::Abstract.'}]}]