A sample of H2 gas (2.0 L) at 3.5 atm was combined with 1.5 L of N2 gas at 2.6 atm pressure at a constant temperature of 25 °C into a 7.0 L flask. The total pressure in the flask is __________ atm. Assume the initial pressure in the flask was 0.00 atm and the temperature upon mixing was 25 °C.