Final answer:
When a gas at 380 torr and 546 K is changed to STP conditions, the pressure is doubled to standard pressure (760 torr or 1 atm), and the temperature is halved to STP temperature (273 K). So, the pressure is doubled, and the temperature is halved.
Step-by-step explanation:
To answer the student's question, first we must understand the relation between pressure and temperature for a gas transitioning to Standard Temperature and Pressure (STP). STP is defined as a temperature of 273 K (0°C) and a pressure of 1 atmosphere (atm). The student asks what happens to the pressure and temperature when a gas at 380 torr (~0.5 atm) and 546 K is changed to STP.
Since STP is at 273 K, we are lowering the temperature from 546 K to 273 K, essentially halving it (273 is approximately half of 546). According to Gay-Lussac's law, if the temperature of a gas is halved and the volume remains constant, the pressure would also be halved. In this case, because we're starting with a pressure of 380 torr and converting to standard pressure (760 torr or 1 atm), we are actually doubling the pressure.
Therefore, the correct answer is that the pressure is doubled, and the temperature is halved when changing from the initial conditions to STP. Hence, the correct option is A) The pressure is doubled, and the temperature is halved.