The slowest step in a step-by-step reaction is called:

Explanation

The slowest step in a step-by-step reaction is called the "rate-determining step" or "rate-limiting step."In a multi-step chemical reaction, the overall reaction rate is determined by the slowest individual step. This slowest step limits the overall rate at which the reaction can proceed, even if the other steps are much faster. The rate-determining step controls the overall reaction rate because it involves the highest activation energy or the most complex transition state.To understand the concept of a rate-determining step, imagine a reaction with several intermediate steps, similar to climbing a staircase. If one step is much taller and more challenging to climb than the others, you'll be limited by how quickly you can climb that particular step. The other shorter steps won't significantly affect the overall time it takes to climb the staircase. Similarly, the slowest step in a chemical reaction governs the overall rate of the reaction, while the other faster steps have a minimal effect on the overall rate.