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: Anaesthesia
[{'content': 'Critical temperature for liquid nitrogen is ? \nSelect and explain. \nA. 36.5degC, B. -20degC, C. -147degC, D. -242degC', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., -147deg C Critical temperature (Tc) of a substance is the temperature at and above which vapour of that substance can not be liquified, no matter how much pressure is applied (Note : Below critical temprature a substance can exist as a liquid or gas depending on pressure). Critical temperature of N2 is -146.9deg C; that means N2 can be liquified below -146.9deg C --> So, liquid nitrogen must be stored below -146.9deg C.", 'role': 'assistant'}]