A coal combustion process generates $13\mathrm{.}4$ kmol$/$h of flue gas on wet basis. Using the composition of the flue gas given below, determine the concentration of O$2$ in the flue gas in ppm$.$

FLUE GAS: CO$2+$ SO$2+2$H$2$O $+0\mathrm{.}4$O$2+9$ N$2$