This implies, pi=100 atm and pf=100−x Now fromthe first order reaction, k=
2.303
t
log
pi
pf
1×10−3s−1=
2.303
38.38×60
log
100
100−x
x=90atm So, the final pressure is, pf=100−90 =10atm Therefore, the pressure of O2 is 90atm and pressure of O is 90 atm so the correct option is 3