This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'The process in which a material melts to form a crystalline phase and a liquid phase known as: \nSelect and explain. \nA. Incongruent melting, B. Congruent melting, C. Sintering, D. Ceramming', 'role': 'user'}, {'content': 'Answer: A \nExplanation: When feldspar is heated at temperatures between 1150°C and 1530°C, it undergoes incongruent melting to form crystals of leucite in a liquid glass. Incongruent melting is the process by which one material melts to form a liquid plus a different crystalline material.\xa0\nThis tendency of feldspar to form leucite during incongruent melting controls thermal expansion during the use of porcelains for metal bonding.\nReference: PHILLIPS’ SCIENCE OF DENTAL MATERIALS, 12th ed page no 430', 'role': 'assistant'}]