Rate Equations: The Rate Determining Step

The rate determining step of a reaction is its slowest step.
The proposed mechanism for this step should align with the rate equation.
The order with respect to a reactant refers to the number of its molecules involved in the rate-determining step.
Example: In the reaction NO2 + CO → NO + CO2, the rate-determining step involves zero CO molecules and a collision of two NO2 molecules.
This reaction is zero-order for CO and second-order for NO2.