In the case of pseudo order

In a chemical reaction, if the actual order is less than the molecularity those reactions are called as “pseudo order reactions”.

For pseudo order reactions , order $\ne$ molecularity

Ex: Pseudo first order reaction , $\text{order,n =1};\text{molecularity ,n }\ge \text{2}$

For all elementary reactions order and molecularity are same but a number of composite reactions are also known for which order and molecularity have different values such reactions are called pseudo molecular reactions (or) pseudo order reactions.