If you start with 0.05 M O3 and 0.01 M NO and the reaction reaches completion in 16 seconds, what is the initial rate of this reaction with respect to O3?

Since we are basing the rate with respect to O3, therefore the rate would simply be the concentration divided by the total reaction time. That is:

rate of reaction = 0.05 M / 16 seconds

rate of reaction = 3.125 x 10^-3 M / second

or

rate of reaction = 0.003125 M / second