A rigid tank is divided into two compartments by a partition. One compartment contains 3 kmol of N2 at 600 kPa and the other compartment contains 7 kmol of CO2 at 200 kPa. Now the partition is removed, and the two gases form a homogeneous mixture at 300 kPa. The partial pressure of N2 in the mixture is
(a) 75 kPa
(b) 90 kPa
(c) 150 kPa
(d ) 175 kPa
(e) 225 kPa