A gas occupiea 500 mL and its pressure is 275 mmHg at 25 celsius. What temperature is need to increase the pressure of the gas at exactly 1 atm and 250 mL?
PV/T remains constant so since 1 atm = 760 mmHg, you want P such that
760*250/T = 275*500/(273+25)
Note: T will be in °K