Rate Constant Graph: Answer Insufficient Data

[temaire]

Homework Statement

A student is examining the kinetics of two reactions, A → products and B → products. The concentrations of A and B were measured as a function of time (in separate experiments) and the following plot was made:

http://img685.imageshack.us/img685/9215/ratel.jpg

The relationship between the rate constants is:
a) kA > kB
b) kA < kB
c) kA = kB
d) Insufficient information to know

The attempt at a solution

I think the right answer is d), since you don't know what the reaction orders are for the two lines. Therefore, you can't compare the rate constants. Am I right?

 

[nobahar]

Hello!
I think the reaction orders are the same, as both the 'curves' are straight (that sentence is peculiar!). If either were dependent on the concentrations, then the rate of change wouldn't be constsant (and the slope wouldn't be linear), as it would be dependent on the concentration at that particular point in time; and as the concentration of reactants decreases, the rate at which the reactants form products would decrease with time. I think!
Hope that helps!