A sample of H_{2} gas (2.0 L) at 3.5 atm was combined with 1.5 L, of N_{2} 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.

A) 24

B) 2.8

C) 1.6

D) 0.56

E) 1.0