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': 'Strength of zinc phosphate is affected by \nSelect and explain. \nA. Temperature of glass slab, B. P:L ratio, C. Consistency of mix, D. Alteration of mixing time', 'role': 'user'}, {'content': 'Answer: B \nExplanation: COMPRESSIVE STRENGTH\nThe fully set zinc phosphate cement has a relatively high compressive strength ranging from\xa0104 to 119 MPa. The set cement gains approximately 70% of its maximum strength in the\xa0first 30 minutes. The strength continues to rise with time and maximum strength is attained\xa0at the end of 24 hours.\nThe strength of zinc phosphate cement is sufficient when used as a base or luting agent. However,\xa0when it is exposed to the oral environment, e.g. temporary restorations, its brittleness and low\xa0strength causes it to fracture and disintegrate. Also, the prolonged contact with the oral fluids\xa0or water gradually reduces its strength. This may be due to the slow dissolution of the cement.\nTENSILE STRENGTH\nThe set cement is weaker in tension (5.5 MPa), thus making it brittle.\nKey concept\u200b\u200b:\nFactors affecting strength\u200b:\n\nPowder-liquid ratio: More the powder, greater the strength.\u200b\nWater content of the liquid:\xa0Both loss or gain, reduces the strength.\n\nRef: Phillips Ed 12th P: 318', 'role': 'assistant'}]