Please I need to make sure which ones are correct

Use the information below to answer questions 17&18. In a hot combustion chamber, oxygen diffuses through a stagnant film of air with thickness L to the carbon surface where it reacts to make CO and CO2. The mole fraction of oxygen at z= L is 0.21 . The reaction may be assumed to be instantaneous. No reaction occurs in the gas film. The chamber is at 1.5atm,1000K, and L=0.1m. The diffusivity of oxygen at these conditions is 0.35cm2/sec. The following reaction occurs at the carbon surface (Gas constant =0.08205atmm3/kmolK) : 4C+3O2==2CO+2CO2 Question 17 0 / 5 pts Which of the following is true? NO2=2/3NCO2NO2=3/2NCO2NO2=2/3NCO2NOO=3/2NCO2 If A is O2 and the remaining gases are B, which of the following is true if you treat this as a binary diffusion system? NA=4/3NB NA=3/4NB NA=3/7NB NA=7/3NB