To answer, we take it that the rate of the consumption of O2 in this item is directly proportional to its concentration in first degree such that,
-dCa/dt = kCa
Solving,
-dCa/Ca = kt
lnCa - lnCao = -kt
Substituting,
ln(0.443) - ln(1.334) = -k(t)
t = 1.1023/k
