Final answer:
Based on the given total pressure of 770 torr, the reasonable pressure for the dry gas would be slightly less, with 762 torr being the most suitable answer from the choices provided.
Step-by-step explanation:
To match the pressure of the dry gas to the temperature when given a total pressure of 770 torr, we need to consider that the pressure of the dry gas will be slightly less than the total pressure due to the presence of water vapor. We know that 1 atm is equivalent to 760 torr. Since 595 torr is less than 760 torr, the pressure of the dry gas should be less than 1 atm if we subtract the vapor pressure of the water from the total pressure.
Since we do not have the exact vapor pressure of water at the temperature of the gas, we cannot calculate the exact pressure of the dry gas. However, based on the options provided, the only value less than the total pressure of 770 torr is 762 torr. The option of 780 torr, 800 torr, and 740 torr cannot be correct as 780 torr and 800 torr are greater than the total pressure, and 740 torr is significantly lower than one would expect given the total pressure, likely indicating a significant temperature change or measurement error.
Therefore, the most reasonable answer to match the pressure of the dry gas to the temperature, given a total pressure of 770 torr, would be 762 torr.