In a period of 6.00 s, 6.00 × 1023 oxygen molecules strike a wall with an area of 2.00 cm2. If the molecules move with a speed of 400.0 m/s and strike the wall head-on in elastic collisions, what is the pressure exerted on the wall? (The mass of one O2 molecule is 5.344° × 10-26 kg.)